A guy goes to a proctologist and says "Doc, I'm feeling a bit uncomfortable down below. Would you take a look?"

He does. "Incredible!" He exclaims. "There's a $20 bill lodged there." He eases it out with some forceps, and immediately a $10 bill appears. "This is amazing", he says. "What do you want me to do?"

"Yeah, well take it out, please, doc, would you?"

He does, and bills continue to appear one after the other, all of which he removes. Finally there are no more.

"Ah, thanks, doc, I'm feeling much more comfortable now. Out of curiosity, just how much was there all together?"

The doctor counts the pile of cash and says, "Exactly $1990."

"Ah," replies the guy. "That explains it. I knew I wasn't feeling too grand."