punk out

verb2

1. •
   (slang) To give up or cravenly abandon something difficult.

   • When the going got tough, he punked out.
2. •
   (slang) To treat as a punk (either as a worthless person or the bottom in a male-male relationship, especially a nonconsenting prison relationship).

   • He knew if he didn't stand up for himself, he'd be punked out by someone stronger.