It means something like: "for real", "seriously"or "I swear ". Also can be used to mean "right away"

another use of tha term "for sure" (fasho) used mostly in the south like new orleans

for real?

Off top--ic, or out of the discussion

off top of the dome suckelle

start off a fight
to spontaneously punch a person in the face
getting a off the top of your head
a saying to start a statement

awesome, dope, cool, good lookin, fine ect.