...He had to produce a fresh sample to make sure he was sterile after having a vasectomy.  There was no place at the doctor's office where he could do it, so he jerked off in his car on the way to the office on Laurel Canyon Blvd. in L.A.  If you've ever been on this road, you know what a feat this was...and to get it in the cup no less!!  Watch him tell the story on Jimmy Kimmel: