When the male of the species becomes physically intrusive with a female in an inappropriate or unwelcome manner.
Also can refer to a preplanned night of debauchery at a party or club when fornication with the opposite (or same) sex is anticipated ("Candy Grab").
"Hey Cameron, that guy over there is candy grabbin on your girl! Let's go kick his ass!"
"Gentlemen, tonight will be the most epic Candy Grab in Alpha Omega Epsilon's storied history."