It happened like this: https://twitter.com/#!/hanneblank/status/141997572339408896

Sperm free, your jimmy needs no hat
Because we now know that
You're sperm free for life

'Cause of irradiation
or genetic mutation
You now are sperm free

Your vas deferens truncation
Caused your girlfriends elation
For you now are sperm free

All of your fornication
Won't increase population
Now that you are sperm free