Here's a few of my favorites that I've seen:
1. Pray for me, I drive 183
2. If you follow me too close I'll pick my nose and flick a booger on your windshield
3. Visualize whirled peas
Then there is the one I want to make:
"D.A.M. — Mothers Against Dyslexia"
Then there is my two favorite buttons:
1. It's my clit and I'll wash it as fast as I want
2. It's my penis and I'll wash it as fast as I want