What is Big-belt-boy?
A FAT LAD WHO DOESN'T WEAR A BELT AND BENDS OVER TO REVEAL A HAIRY CREVICE/CRACK.
"OH MY GOD! TERRY'S A RIGHT BIG-BELT-BOY, WHEN HE TIES HIS SHOE LACES UP YOU SEE THE TERRIBLE SIGHT OF THE HAIRY CRACK OF HELL
See fat, crack, hell, crevice, belt