What is Mfcs?
1.
MotherFuckerCockSucker
This is a more "mixed company" friendly way to express the above expletive. This can be used as an adjective but it's more commonly just used as an angry outburst.
"That MFCS just rear-ended my new car!!"
or
Joe - "Hey, Tom, I just saw Pete with his tongue down Kelly's throat. Isn't she supposed to be YOUR girlfriend?"
Tom - "MFCS!!!!!"
See
2.
Multiple Facial Cock Slaps
In the porno that Josh rented, it showed graphic acts of MFCS.
See