You drastically misinterpret facial expressions.

You opened the door and saw my friend and I looking at you, which seemed to flatter you since you looked so pleased with yourself. You stood in line behind us, much too close for conventional American standards of personal space. I thought you were either just drunk or foreign (or both) until I realized you thought we were interested in you. No, sir, we were not physically attracted to you in the slightest. What you mistook for nervous sexual tension was actually more like legitimate fear, since at that moment we had just learned from the cashier that the convenience store had been through an armed robbery 10 minutes earlier and we were watching out for suspects.