The categories are as follows.  You need only 24 of them.  The more creative, the better off you are.  Base pictures are worth 10 points, bonus points are listed in parenthesis.
 

1. Policeman (-3 to +3) Example:  A policeman in his car zipping by will only be worth 7 points but you getting the policeman to put handcuffs on one of the players will definitely be worth 13.
2. Tree (-2 to +2)
3. Street Sign (the stranger the better) (-5 /+5)
4. Television show through a store window (-5/+5)
5. Airplane on the ground (-2/+2)
6. Hairstyle (-3/+3)
7. People on the ground (-1/+1)
8. Traffic accidents (-6/+6)
9. Natural Disasters (-3/+3)
10. Hotel Clerk (-5/+5)
11. (blank) crossing sign (-3/+3)
12. A house under construction (-3/+3)
13. Albertson's grocery store (-2/+5)
14. A parrot (-2/+4)
15. Domino's delivery guy (-6/+6)
16. A train (-5/+5)
17. An ugly car (-5/+5)
18. A fax machine (-2/+2)
19. Holes in the ground (-3/+3) (Size is paramount)
20. A lady with blue hair (-2/+2)
21. Strange video game (-2/+2)
22. A famous person (-7/+7)
23. A billboard (-4/+4)
24. Farm animals (-3/+3)
25. Sporting event (-3/+3) (Not necessarily professional)
26. Weird named restaurant (-4/+4)
27. A swing set (-2/+3)
28. Fire (-4/+4)
29. Earth (-3/+3)
30. Air (-2/+2)
31. Water (-3/+3)
32. Pizza (-5/+5)
33. Toll booth taker (-3/+3)
34. Interesting individual (-6/+6)
35. Movie marquis (-3/+3) (altered is better)
36. Bedroom furniture on highway (-6/+6)
37. A priest (-5/+5)
38. A prostitute (-4/+4)
39. A pet cemetery (-1/+1)
40. An American Mini-Mart cashier (-2/+2)
41. A gun (-5/+5)