When a species of the male origin attempts to discreetly glance at a females breasts. He may do so in a number of ways, using binoculars, his eyeballs, spectacles, poking holes in newspapers, pretending to be looking into your face, using the excuse of "I have lazy eyes, they don't always look where I mean to!" Peek-A-Boobing is also quite often failed, and quite sadly, the female most definitely notices and the fool proceeding with the Peek-A-Boobing ends up doing a boob-tacular stare down.
Terrance: "Hey girl what's up I was just walking in the park today when I saw this cute little puppy being taken away by a huge flying eagle creature-like-thing, and I decided to rescue it."(Tells more of this cocky story, while his eyes slowly shift from the girls eyes to a different pair of her "eyes".
Francine: "Terrance, stop Peek-A-Boobing! I know they are beautiful and you can't help but farther your breast obsession, but I'm not here for a show!"

Terrance: Hangs his head in shame for being caught needing Peek-A-Boobing practice.
by Copywrited this phrase! August 9, 2011
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a nipple that seldom remains concealed by a bra, or any article of clothing, meant to conceal it - usualy occures when an areola is significantly larger than that of the average nipple
"I love when chicks with silver-dollar nipples wear scoop-neck tops... every time they move, there's a PEEK-A-BOOB!"
by James Goldstein June 4, 2007
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When half or majority of a boob (perferbly a female's) slips out of clothing by accident
"Man, Stacey's peek-a-boob incident today was so hot."
by Shirtlesssleeves March 30, 2014
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A much better alternative to the popular term "nip slip".
Girl 1: OMG, I totally had a nip slip while I was talking to a guy today.

Girl 2: You mean a peek-a-boob?
by petopher May 26, 2014
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