Bert met Flo in a bar one night and began buying her drinks. They
 hit it off pretty well, and soon Bert suggested that they go to
 his apartment for some extracurricular activity.  It wasn't long
 before they found themselves in bed making passionate love.  As
 they were making love, though, Bert noticed that Flo's toes would
 curl up as he was thrusting in and out.
 
 When they were done, Bert laid back on the bed and said, "I must
 have been pretty good tonight. I noticed your toes curling up
 when I was going in and out."
 
 Flo looked at him and smiled. "That usually happens when someone
 forgets to remove my pantyhose."