In June 1980, "Weird Al" Yankovic first performed "Won't Eat Prunes Again" on The Dr. Demento Show. Shortly after, he rocked it live at Cal Poly. Audio evidence above.
That was such a dirty trick
Boy, it really made us sick
Well it looks like we've been done in by the prune
Still the memory lingers on
I been livin' in the john
'Cause I've had the runs since Monday afternoon