When the whole crowd falls silent and joins in the act of praying before a sporting event they are invocating. Usually occurs just before the singing of the national anthem.
Was coined by two dumbasses during an invocation at Callaway Raceway in Fulton, MO. in 2009.
Dude shut up, they're invocating.
Person 1: "Wanna play Genius Invocation TCG?"
Person 2: "Na, I'm still doing the arcon quests"