Well, the funniest typo I ever made involves no dirty words. When I was typing a report on global climate change, at one point I typed something like "eventually the whole planet will be in danger" (I forgot exactly what the phrase was). Except when typing the word "planet", I didn't hit the E key hard enough, so the phrase ended up being "eventually the whole plant will be in danger" instead.
The interesting part about this was that the spell-check didn't detect this typo because plant is a real word, and a noun like planet. So this typo made it to my final draft without detection. Then, five minutes before turning it in, I read it over and found this typo. I had to cross the word out with pen and write "planet" just above it.
Other typo moments I had are not typos, but "writos", where the error is in something written. The funniest example I had of this was when I was writing a lab report for a chemistry class. At some point in the report I had to write the word "anion" (which is a negatively charged ion, for those of you who haven't studied chemistry). When I got the graded report back, the instructor had crossed out that word and wrote "anion" above it. At first I was confused, but when I looked more closely, I saw that there wasn't much of a tail on my A, so the word looked more like "onion". No wonder the teacher corrected it!
(Note that the last example is not an easy typo, because A and O are on opposite sides of the keyboard.)