Or, if you're not playing three fouls, maybe he scratched needing one, and by getting him to foul again from the corner hook he will be needing three.
Or, if you're playing straight pool, and he scratched for two in a row....
In any case, the corner hook by ball-in-hand placement is not part of any pool game.
In addition, if you happen to be in the jaws but not frozen, it is not allowed to jam the cue ball against the jaw and hold it there for the freeze. Such "trapping" is explicitly forbidden by the rules at onepocket.org. To get the freeze, you have to play a soft, normal stroke with no double hit. See Rule 6.6 at
http://www.onepocket.org/official-one-pocket-rules/