Hehe.. that is such an appropriate bumper sticker for a jeep ;)

I haven't seen any that immediately remind me of anime 
characters, but one of my favorites was:

BUMPER STICKER   

It's simple black bold type on a white background... ahh.. I still 
find that insanely, funny. So i'm easily amused.

I do have quite a few bumper stickers on my car. I 
actually see people reading them all the time. It makes my day 
when people can smile/giggle/laugh at my bumper stickers.

My bumper sticker phrases:

"Therapy is expensive, poppin' bubble wrap is cheap - you 
choose"

"I poke badgers with spoons"

"I throw peanuts at old ladies"

"Rock is dead. Long live paper and scissors"

"Worst sticker ever"

"Animals taste good"

Glad I could share something so fun. Wish I had a cel to show. 
Oh well.

The easily and perpetually amused,
~Tara