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.
We went to Mcdonalds and ordered 5 big macs, scraped off all the secret sauce and i mcmaced her all night
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.
Cashier: Sir may i take your order?
Customer: why yes could i have a MCMAC MCMAC MCMAC!
Cashier: OMG WHY WOULD YOU PUN...
Customer: *jumps over register and continues punching Cashier*
Cashier: ok ok, here's your mcmac