Every player has a ritual. Some have a standard pregame meal. Some listen to the same music. Others have superstitions before every game. For Doug Gilmour, one of the rituals for which he became well known was tucking in the left side of his hockey jersey.
The practice started when he was playing for St. Louis and all the jerseys were one size. Doug, being a smaller player, found a way to keep his jersey from hanging low by using a skate lace to keep it up. As the players got jerseys in their own size, the habit stuck and he just started tucking in the left side of his jersey so that he could better see the puck (Doug shoots left).
Given that old habits die hard, whether it's an alumni or charity game, you can still find Doug playing with his jersey tucked.