whippin' tits
If someone is whippin' tits, they are accomplishing their goals in an efficient manner, aka kicking ass and possibly taking names.
"I am really whippin' tits on this homework."
"Can't believe you got that floor laid so quickly, you must have really been whippin' tits."
"Can't believe you got that floor laid so quickly, you must have really been whippin' tits."