The story
Deriving from the likelihood of being checked off the play and losing possession of the puck, being a suicidal act in puck possession.
Etymology from Wiktionary, CC BY-SA 4.0.
suicide pass
Today it means: A pass going up-ice where the passee must look behind towards the passer for the location of the puck, therefore being left unaware of opposition players further up-ice, allowing the passee to be checked from a blind spot. Full definition →