A common phrase or term used in hockey language that means "to score a goal". When a goal is scored in the NHL, the red light behind the net that the goal was scored in will turn on, and that is the basis for the term "to light the lamp".
Along with the red light behind the net, a siren will be activated every time a home team scores a goal in the NHL. The "lighting of the lamp" serves as a signal for the siren to be activated. While the siren is activated only when the home team scores, the "lamp" will be lit anytime a goal is scored, regardless of which team scored it.
When a player is on a "hot streak" and is scoring goals in consecutive games, it is said that this player continues to "light the lamp". Furthermore, the term "to light the lamp" is used frequently in the hockey community as part of the title of different hockey-related events and publications.