When your dick comes out of the hole in your boxers inexplicably or when you can see the outline or bulge or your dick while wearing any kind of athletic shorts or sweatpants.
Hey dude you might want to stuff some toilet paper in your shorts cause you have a pretty bad Peeping Pecker.

Hey make sure you have a blanket tonight you don't want to have your parents see you with a Peeking Pecker in the morning.
by Freebirdzack January 12, 2015
Get the Peeping Pecker mug.
when your pecker pokes through the slit in your boxers. usually happens in gym leading to ultimate embarassment
I was changing in the locker room when my pecker peeped and everyone saw my tiny willie
by adsfajsfklajsd; June 3, 2009
Get the pecker peep mug.