Sesame chicken describes a scrotum peeking out of a guy's shorts. The coloring, texture, shape, and size of the visible portion of the scrotum is oddly similar to a
piece of sesame chicken from a Chinese
restaurant.
This is not a flattering situation. It usually happens without the guy knowing about it. It is most common in summertime,
when the guy is (1) wearing boxers and (2) wearing loose fitting shorts.