The most delicious and fattening of all McDonald's products. It can only be ordered from their secret menu, to access this secret menu you must punch a cashier in the face while shouting McMAC!! repeatedly. If the cashier is still alive, he must then (company rules) proceed to give you a McMac.

A mcmac is the sexual action of filling a womans vagina with big mac secret sauce then eating it out, therefore bypassing the unbearable fishy taste associated with a vagina.