Many restaurant offer birthday specials = go with group of 4 to 6 people, birthday person eats free. Some valid for +/- 1 week, some on exact day of birth only.
Le Bifthèque used to be one of the few restaurants that offer free meal for birthday person, NOT SURE if they do it anymore. Not sure if West Island/airport location is still open. Boucherville is still open, outside of the island. Please do your enquiry.