An illegal contraction of "fucking" and the already colloquial "dayum
". Used for further emphasis when there's no other word to express how epically shocking something/someone was in an event.
*Person A enters with crutches and a bloody nose with his neck twisted 180 degrees.*
Person B: Gawd fayum! You got fucked up, nigguh...
Person A: I know...FML.
"Be Like Skizzo."