What is Ygbsm?
1.
During the Viet Nam war, US pilots were getting shot down because of surface to air missile
Currently, the term is used as an exclamation of shock or disbelief.
"Hey, dude, I heard there was another hurricane headed towards NoLo"
"YGBSM!"
See
2.
you gotta be shittin me
boss---you need to (insert the impossible here)
employee---ygbsm
See