Wiktionary
slack off
vb. To be unproductive; to not perform one's duties.
WordNet
Usage examples of "slack off".
Training didn't exactly slack off, but it did stabilize, lest the men become overtrained and dulled by the routine.
If you slack off, and she walks the wall at the same time, I can have her up and in that nook with me in that time.
So they're going to slack off on me, thinking that on account of I suddenly start banging white, I lost my place.
He thought he'd come to terms with getting older and slowing down, but he realized that didn't mean he could slack off.
If Boyson had picked up his bills for the next two years, he would have been able to slack off and only enter for the big prestigious competitions, gradually devoting more and more time to politics.