A 'Boy-off' is a person who ditches you. This person will 'boy' you off often in favour of doing something else.
"Oh Ollie is such a boy-off"
"Holly just boyed me off for Jenny"
"Just boy your work off an come see me instead?"
to be rude or to ignore or to walk away from someone.
oi! he just walked away from me! smack that boy-off!
Pernounced (B-o-y-o-f-f), is commonely used when claiming someone is full of shit. Coming from the ghetto of Vernon Hills, it was created to say "bullshit" in a new way. When saying it, one must raise one leg and slap it with your hand, signifying BOYOFF!
Brett: I got you pack of squares
Taha: Fuck that, your pussy ass doesn't have anything. Boyoff you fuck. (While slapping leg)
George: I'm not a sardine...