JK Rowling herself thought these were hilarious
1. Ask him why he 'doesn't have such a cool scar?'
2. Laugh at him.
3. Wake him up by singing Beach Boys songs in his ear. 'Round, round, get around, I get around...'
4. Knit him things. Really hideous things.
5. Give him kangaroo-ears for a month.
6. Smile during Death-Eater meetings and say you taught him everything he knows.
7. Chew bubblegum all the time. Should he address you, your only response will be a series of huge bubbles in quick succession, the last of which will burst everywhere and make a mess.
8. Dance the Funky Chicken.
9. Ask him when was the last time he took a bath.
10. Pat him on the head and give him flowers when his plans are foiled yet again.
11. If you ever need to say 'Like taking candy from a baby', be sure to add 'Of course, SOME of us might find that harder than others.' Stare pointedly at him.
12. Play 'knock-&-run' at his bedchamber door late at night.
13. Call him 'The-man-who-let-the-boy-live'
14. Ask why the Dark Mark couldn't look like something 'more socially acceptable?'
15. Insist that you have met chunks of cheese with more cunning plans than his.
16. Pinch him. Make sure he squeals.
17. Be cheerful.
18. When he tries to impress you with his powers say 'Awwwww, lookit. Voldie's got a twiggle!'
19. Try to teach him to play a mouth organ.
20. Roll your eyes during plotting sessions and say things under your breath like 'You're the boss, boss' or 'It's your funeral.'
21. Greet him in the mornings with a sarcastic 'My sir, you look particularly menacing today.'
22. Taunt him about his middle name. 'Marvolo? Whats that, a washing detergent?'
23. Keep a 'good-behaviour chart'. Award points and give out gold stars.
24. Magic-marker Potter-style glasses on him while he sleeps.
25. Apparate into and out of his room rapidly. Do this non-stop for an hour. *poof* there *poof* gone *poof* there....
26. Play cards with him. Tell him he has no poker-face and how does he expect to rule supreme without one?
27. Let off party-poppers in his face whenever the urge strikes you.
28. 'Did you even HAVE a girlfriend? Like, ever?'
29. Get a pair of finger puppets closely resembling himself and Harry Potter. Re-enact all of Harry's victories over him in a spectacularly childish way. Be sure to give them both squeaky voices.
30. Anytime he enters any room, insist on entering first and announcing him grandly.
31. In these announcements, fake a trumpet noise and give him an equally fake drumroll.
32. Exclaim sarcastically 'You're breakin' my little heart here, o dark one' whenever he starts to talk of what has caused to become who he is.
33. Encourage him to 'think happy thoughts!'
34. Ask him to give you written summaries of his sinister plots for revenge and war. Correct his spelling.
35. Mock his choice of Quirrel as a 'host'.
36. Tell you think a yoga class could 'cure him of his wicked ways'
37. Get the song 'Mr. Tambourine Man' stuck in his head.
38. If he's having evil-plotter's-block in one of his scheming sessions 'Wingardium Leviosa' a light bulb to float above his head. Turn it on. Look offended when he gets angry and say you 'thought you were helping!'
39. Tell him constantly to stop repressing his anger.
40. Buy him a stress ball.
41. Hint that he is only a character in a book and will never triumph.
42. Call him Tommy-boy.
43. If you're feeling gutsy, call him Voldie-poo.
44. Whack him in the arm and say 'mosquito' - every few minutes.
45. Say he 'looked better under the turban'
46. Eat his pet snake. Offer him some.
47. Endeavour to teach him to steeple his fingers, lean back and say 'Eeeexcellent'.
48. Start drawing outlandish parallels between his life story and 'Star Wars'. Talk at great length.
49. Be generally in awe of him and never look away.
50. 'Imperius' his Death Eaters into a rousing chorus of 'All Things Bright And Beautiful'
51. Shower him with confetti and rice, anytime you think he needs to make a 'grand entry'.
52. Paint all the Death-Eater masks with bright colours and glitter.
53. Throw him a 'care-bears' themed birthday party.
54. Tell him what Snape's really up to.
55. Politely exclaim now and again that you 'don't know how he can be so afraid of dear old Dumbles'
56. Sing 'California Dreamin' at the top of your lungs when he's trying to have an 'evil moment'
57. Should you ever be eating with him - drum tunes with your cutlery, play with your food and blow bubbles in your chocolate milk.
58. Ask him to dance a polka with you.
59. Work cutesy phrases like 'pushing-up-daisies' and 'smooth-as-a-baby's-bottom' into conversation as much as possible.
60. Ask him if he's sure 'the whole evil-maniac-out-for-power-and-revenge thing isn't getting a bit old?'
61. Get him to play 'Twister' with you.
62. Tell him you know this great therapist in London....
63. Throw tupperware parties. Insist he sit through them.
64. Tell him you've met plently of people more evil than he.
65. Hide his teddy bear. That ALWAYS makes him cry.
66. Get him a plant. Act mortally offended when he doesn't water it and it dies.
67. Steal, snap and bury his wand.
68. Tell him Lucius did it.
69. Give Rita Skeeter full knowledge of his whereabouts and contact details.
70. Remind him that he isn't even really alive.
71. Write him a theme song. Start singing it whenever he is about to do or say something particularly clever and nasty.
72. Offer to sacrifice Draco Malfoy 'to the cause'
73. Insist on reading him bedtime stories. Include 'The Ugly Duckling'
74. Make vague allusions to Harry Potter being his son.
75. When he's done something particularly nasty - cross your arms, waggle a finger and say 'Now now, do you really think Salazar would have approved of that?'
76. Ask him how he can possibly wish to harm a single hair on the head of 'that sweet, innocent, cute little boy.'
77. Tell him Wormtail has a crush on him.
78. Finish all your sentences with the words "in accordance with prophecy."
79. Leave disgusting and rotting dead things near him. Insist that it is 'Aromatherapy'
80. Begin any question you ask him with 'Riddle me this!' Emphasis on Riddle.
81. Do not EVER act in the slightest way intimidated by him. Treat him as you would an eccentric aquaintance.
82. Cuddle him at random moments.
83. Sign him up for Little-League.
84. Ask him why he's afraid of a frail old man with a beard the size of a beehive and can't fight babies.
85. Throw biscuits at him. Constantly.
86. Tell him you think evil master plans of world domination are 'kind of girlie'
87. Quote Argus Filch. Insist HE will one day rule the wizarding world.
88. Wonder aloud whether the name Voldemort commands as much respect as, say, Potter or Dumbledore.
89. Mimic everything he says in a sing-song voice.
90. Mimic everything he does with exaggerated limb-movements.
91. Write sonnets for him.
92. Insist he help you with the newspaper crossword every morning.
93. Follow a few paces behind him, spraying everything he touches with a can of disinfectant.
94. Tell people he's 'really just a big softie'
95. Psychoanalyze him. Conclude that he is 'mildy depressed' and 'a bit of a control-freak'.
96. Mock his baldness.
97. Smile and say loudly 'Who loves you, Volders?' at inopportune moments. (Ie: another of his attempted 'evil moments')
98. Get him drunk.
99. Drag out a banjo at Death Eater revels and start playing 'Kumbayah'
100. Let him catch you trying on Death-Eater robes.
101. Be Harry Potter. Be alive.
