Tomorrow is my birthday. I've heard and seen about every April fools day joke ever. BUT #7 takes the cake... http://www.lifebuzz.com/april-fools/
We do #9 all the time. Usually it is on the back of one of the redneck boys trucks and says "honk if you support gay marriage" or some shit. That one never gets old.
Mine too. When I was 20, my girlfriend gave me a fake letter from planned parenthood confirming her positive pregnancy test. She had gotten their letter-head, and even stained the paper with her own tears. In hindsight, I'm pretty impressed.