The only one I ever had was like the Christian fish, but with legs and it said “Darwin” inside the fish. I lived in the Bible belt, and it was fun to antagonize the fundies. 
My cars are the kind where I can reply, Laugh but its paid for…
So
I have an SCA sticker.
I have always wanted a " Bad cop, no donut" sticker… 
Schmart! I have a sticker machine and made a reverse sticker to go in the window, facing out. After 9-11 I wanted something that didn’t make me cringe, so I made my own.
Other than that, no stickers in almost twenty years. My first and only bumper sticker was an ‘I 
(hate) liver’ sticker my sister put on my car. Which was cute, but a lie. If my mom cooks it, liver is okay. So I felt like a fraud for years, falsely proclaiming a hatred I did not feel.
I personalize my car window shades instead of bumper stickers. No paint damage!
I’m firmly convinced that placing stickers on my car activates a curse. Three times I waited a good while before personalizing my vehicle, and soon after they would DIE…I don’t mean they’d need repairs, I mean they would DIE, generally going out in a huge puff of black smoke.
This one will remain as generic looking as an Acclaim can be. I KNOW it will be healthy because of my vigilance in refusing to personalize it.
shhhh!
The problem with clever bumperstickers is that they’re only clever once, so I avoid those. Anything serious I don’t feel the need to display to the world, so I avoid those. And so, my car is speechless.
I did see one I loved enough that I considered getting it though - “Jeez if you love honkus”.
I always found this an admission that Darwinism is a religion, just like Christianity.
I personally have no bumperstickers, but plan to when I have children. I want George Carlin’s suggestion, one that says, “I’m the proud parent of a child whose self-esteem is sufficient enough he/she doesn’t need me to celebrate his/her minor academic achievements on the back of my car.”
I’ve actually been thinking of having a:“I club baby seals for Halliburton” sticker made. Just for the hell of it.
As to the OP; nothing is on my truck. No one has ever changed their mind over a bumper sticker, so I see no reason to express any opinions that way.
I can’t see any upside to a political bumper sticker–as Pullin said, nobody’s going to suddenly come around to my way of thinking because of a witty phrase on my vehicle–and there’s a definite downside: I’ve had friends who suspect their unpopular bumper stickers were the reason their cars were vandalized.
As for funny ones, I can’t think of any joke that would remain funny for the average life expectancy of a car.
During election years I’ll put on a Libertarian sticker and take it off after we loose.
The rest of the time I have a sticker promoting my mothers website and business. … Which now that I think of it, is funny since I’m in NC living 800 miles away from her.
I have two small stickers on the bumper of my car. One states that I’m a member of AAA and the other reads “Merge Records” (my favorire record label). No political statements or witty phrases for me.
I have a bunch. :o
“A PBS mind in an MTV world.”
“Without our families, alcohol wouldn’t be necesary.”
“Smile…it’s the second best thing you can do with your lips.”
“It’s only kinky the first time.”
And I can never remember the last one.
I have a Transformers Autobot insignia sticker (the symbol displayed by the good guy Transformers, robots that changed into cars) centered in my back window. That’s it.
No stickers. I have nothing to say to anyone. I’m giving the world the silent treatment.
LOL!
currently only U.S. out of Pangea but I’m ordering another. And maybe this. Lawds I loves me cafe press. I get to put my twisted mind to paper.
Holy shit, that’s awesome!
No bumper stickers for me. Never saw the point of wearing my opinions on my butt.
I put a KEEP IT SIMPLE, STUPID sticker on a pickup I once owned. I’ve since gotten rid of it and have returned to my ‘no stickers’ position.
I just wish I had the guts to use this for a sticker.
Yes. God Bless John Wayne and Impeach Earl Warren.
That’s a joke by the way…