Oh god... my wife and I got the nastiest set of rug burns you have ever seen... we were not married at the time, and we were visiting some reletives out of town. Since there was family all over the place, and we had to share rooms, we didn't... well you know, have a lot of chances.
But we got our chance and snuck away into one of the bedrooms. We couldn't do it on the bed because there were all these cloths stacked up there, and we were kind of in a hurry. So we just got down on the floor. Well... what was going to be a quicky, turned into... a little more than that. And the next thing you know, we're laying there going... "man, my knees hurt... ouch, my back hurts... Oh SHIT" Yeah, we had to try and explain that one... they didn't believe us...