This phrase can be broken up into two parts. "Tax That Ass" is to have sex with a female in a manner that depletes the energy of the female; in a sense, "taxing" her stamina. The second part, "Like Woah," emphasizes the taxing of the ass.
A plate of brown consists of foods that have little to no nutritional value, and are typically deep fried. A true plate of brown will also be accompanied by a dark soda.
When finance content creators rent out fancy cars and flex cash to seem richer than they really are in order to promote and sell their “get rich quick” courses.