Steve and Fiona were making passionate love in Steve’s Sandman Panel Van when suddenly Fiona, being a bit on the kinky side, yells out "Oh fat boy, whip me, whip me!" Steve, not wanting to pass up this unique opportunity, obviously did not have any whips to hand, but in a flash of inspiration, he opens the window, snaps the antenna off his van and proceeds to whip Fiona until they both collapse in sado-masochistic ecstasy.
About a week later, Fiona notices that the marks left by the whipping session are starting to fester a bit so she goes to the doctor. The doctor takes one look at the wounds and asks "Did you get these marks having sex?"
Fiona, a little embarrassed that she has slept with Steve (let alone that she allowed the kinky bastard to whip her) eventually admits that, yes, she did.
Nodding his head knowingly, the doctor exclaims, "I thought so, because in all my years of doctoring you’ve got the worst case of van aerial disease that I’ve ever seen."