Never underestimate Canadian hospitality. As a mosh pit broke out early in Toronto punk band PUP’s Monday night set, singer Stefan Babcock reminded the Starland Ballroom crowd — as a kindergarten teacher might nudge a class of 5-year-olds — that everyone should leave the concert with two new friends and zero new enemies. He proceeded to check on the pit throughout the night, at one point even helping a fan find their keys. “Thanks,” was Babcock’s gentle refrain Monday, upon the conclusion of nearly every morbid and sardonic tune expressed by the four-piece rock group. It was telling juxtaposit…