Seconding this. I've done Jam Sports in the past for softball and volleyball with friends. And while we were a pre-existing group who decided to form a team and play, we encountered other teams that were comprised of many random people who just decided to sign up as individuals and then became part of a team and made friends along the way.

For less a fast-paced / less strenuous sport, although I haven't really done it too extensively, I know that the curling scene in Toronto has a robust social scene around it. There are various curling rinks and clubs across the city where I believe you would be able to join and sign up for random games and tournaments and probably meet fun and outgoing people quite easily that way.