Brendan Gallagher was ejected from the Canadiens game Thursday night for throwing a vicious elbow at his opponent's head ... and now, fans want to see him sidelined for a while for the dirty play.
The incident happened during the Canadiens' game against the Islanders at the Centre Bell Arena in Montreal ... when Gallagher tried to stop Adam Pelech from getting deep into the neutral zone.
Video from the game's broadcast shows right as Pelech crossed the blue line .