If he checked someone else on your team earlier.
If you tried to fight him and he refused.
If he has it coming.
If Don Cherry would approve.
If Mike Milbury would approve.
If a drunk guy in the upper deck would approve.
If punching people is the only skill you offer your hockey team.
If a message must be sent.
If there needs to be a change in momentum.
If he has, like, a big, stupid, punchable face.
If you’re just having a bad day.
If he knows what he did to deserve this.
If he needs to learn what he did to deserve this.
If the crowd needs to be fired up.
If he needs to be put in his place.
If there’s some bad blood.
If the other team is scoring too much.
If your team is losing.
If you’re just really into MMA right now.
If it’s a rivalry.
If enough is enough.
If your toughness is in question.
If it’s a warning.
If it’s a preemptive strike.
If you’re just policing the game.
If [anything that can loosely fit under a vague definition of a "code"]