Boris Katchouk was just trying to help.
When Cal Foote lost his stick in the defensive zone, his teammate was simply trying to return it to him. Unfortunately, you can’t do that.
Katchouk was sent to the box for throwing the stick.
From Rule 10.3:
A player will be penalized if he throws or shoots a stick to a teammate on the ice […]. A minor penalty shall be imposed for an infraction of this rule.
Rule 53.2 gets into more detail:
A minor penalty shall be imposed: (i) For throwing a stick on any player on the ice who throws his stick or any part thereof or any other object in the direction of the puck or an opponent in any zone.
Next time, perhaps Katchouk will be a bit more mindful about how he helps out his teammates on the ice.