Bumperstickers can be quiet statements of personal effort (like the recovery icons), political statements, either direct or sarcastic (like Keep Davis Boring), or just witty amusements to publicly comment on the world.
I'll start off - I saw a sticker the other night on someone's car that read, "Don't Drink and Park. Accidents Cause People."
"Save a tree. Eat a beaver."
"Alcohol and calculus don't mix - never drink and derive"
"Born okay the first time."
"Dip me in honey and throw me to the lesbians" -seen in South Davis
"Draft the SUV Drivers First!"
"The only Bush I trust is my own"
"This car is a status symbol. It symbolizes that I am poor." -seen on a 90's convertible cabriolet
"I (HEART) 63MPG" - seen on a Honda Element Hybrid in West Davis
"Forty-Six & Two Are Just Ahead of Me" - seen on a Honda Civic on campus.
"MetalOn" - my friend Danny's car (I'll get a picture soon).
I saw BENZFTW today >_< —StevenDaubert