One of the great features of football being played when the final score doesn't mean a dang thing is the ability to spend time watching, observing faces on the sidelines. There's an air of ... not carelessness, but freedom to relax on the sidelines, joke with teammates.
It's especially evident in the veterans who never touch the field in early preseason action and the starters who get to drop their pads at the locker during halftime.
For some, including those fighting to earn spots or to prove why they belong in a chance they've been given, the football armor stays on but the emotional armor comes off for the laughs to come out.