MFDD 

Motherfucking Dangerous Device

Something that is considered extremely dangerous to a person's health and safety.

LT: Private, be careful with that MFDD! It can explode at any second!

PVT: Yes sir!

MFDD by Got_You May 2, 2019

mfdd 

MFDD is a military slang term for a potentially apocalyptic device and it stands for..."MOTHER F@$#ING DOOMSDAY DEVICE."

"Noble 6" threw an "mfdd" into a covenant ship and blew it all to hell. In case you didn't know, that was a reference to the video game HALO REACH.

mfdd by DykesVespar September 8, 2010