I sometimes wake up with a wet, sticky spot on my underwear that's not pee. So, what is it?

Chances are that you had a "wet dream" — something that can be embarrassing and confusing, but is completely normal. A wet dream is when a guy ejaculates (or "cums") while he's sleeping. During ejaculation, semen (the fluid containing sperm) comes out of the penis and this is what you noticed on your underwear. Wet dreams usually happen during dreams that have sexual images. Sometimes guys wake up from a wet dream, but sometimes they sleep through it.

Wet dreams begin during puberty when the body starts making more testosterone, a male hormone. Some guys may feel embarrassed or even guilty about having wet dreams. But they're are a normal part of growing up and you can't stop them from happening. Most guys have wet dreams at some point during puberty, and even sometimes as adults. Wet dreams usually happen less as guys get older, though.