As you may know, in the game Animal Crossing you can design your own textures to use on your little guy (or gal)'s shirt and hat. If you're feeling somewhat unimaginative, check out some of these...
http://ickster.tripod.com/textures/
http://www.vgmaps.com/Other/SpecialStuff/index.htm
Quite a few are extremely well made and wouldn't look too shabby on your character's t-shirt.
(Can't post all my favourites in thread because most are in PNG format.)
Some mentionables:

(Phil

)

(Danny

)

(Hi and welcome to Call for Help, I'm Chris Pi- HEY! WHAT THE HELL ARE YOU DOING!? GET AWAY FROM MY CHERRY TREE YOU SONOFABITCH! I'M TALKING TO YOU, SWINE! YEA, YOU! DON'T GIVE ME THAT LOO- HEY! HEY! GET BACK HERE!)
Ahem...
Some people over at IGN Boards have created (or ported) textures you can use when designing to face of one of the cats you meet in the train.
Don't want your feline friend to succumb to the horrors of something like this?
Then give him a Wario mug!
Or better yet...
GARFIELD!
I hope this has been informative or at least in the slightest bit thought-provoking. Danny... looking forward to sending you a cute little stuffed animal...
OF PAIN!
Ok, that's Danny's joke but nevertheless I w- uh... I...
*runs away*