There's a double usage to biff. Mainly in
Northern Scotland.
Biff means "to go" or "has gone".
Biff also means, in polite terms, "go
away and leave me alone", similar to "Fuck off".
1a. "Gonna biff up the shop in a few and get a 4 pack"
1b.
"Where's
John?"
"He biffed over to his Mum's earlier to get his washing done"
2. "Biff off,
prick... I
don't wanna deal with your shit"