Tear you a new asshole, means to get cussed out degrade and make you feel like an idiot because you did something you wernt supposed to do or messed something up in some way shape or form
Ex. Did you hear John wrecked his dads truck last night? Sucks to be him His dad is going tear him a new asshole.
Ex. John showed up to work late two days in a row, the boss is looking for him he's about to tear him a new asshole.
Tear you a new asshole