St George breaking a jaw by flexing

An ex latched on to his wrist and tried to bury its teeth in his bicep. He flexed and cracked its jaw, then swung his elbow up to send it sprawling. Another one fell onto his back and he shrugged it off.

Excerpt From Ex-Patriots, pg 541
Peter Clines
https://books.apple.com/us/book/ex-patriots/id585738393