-When a friend or person prevents one from hooking up with a potential mate.
-When a 3rd party male comes in between a couple or steps in between a conversation between two people of the opposite sexs and cuts the tension, while the guy or girl attempts to flurt with the other sex. (aka Clock-block)
"Dude!!..get the fuck out of here, dont a-square me."
"Yo Sam, check that douchebag out,he's with your girl...go a-sqaure that shit.
"I a-sqaured your drunk ass, shes fucking brownote