Wiktionary
sag off
vb. 1 (context idiomatic English) To skive, to not attend school when required to do so. 2 (context idiomatic basketball English) (rfdef: English) 3 (context idiomatic nautical English) (rfdef: English) 4 (&lit sag off English)
Usage examples of "sag off".
There are still times when the vacantness shows up behind his eyes, when the countless years of his life seem to sag off him like a skin too large.
She was being sailed well but her captain was letting her sag off, so she'd have to tack to stay up to windward .
In turn one or two other ships, forced to bear away to avoid a collision, would be unable to get back into position and would themselves sag off.