"Peeps" are the colored sugar covered marshmallow candies originally designed to look like baby chicks. They now have bunnies and all other shapes. They are BIG at Easter time, and I don't think many American kids go long without eating some,. They hit the stores like an army around Easter...and a few other holidays. At Easter, you can't go ANYWHERE without seeing Peeps. (I believe they are called that due to the sound baby chicks make - I might be wrong, though.)
...so it is a play on words for the all famous "peep" show where men used to be able to take a "peep" at mostly naked women. it's a relatively old term not useed much in the US any longer, but everyone DOES still know what it means....even if you see those things called by other names now.