Jerry Seinfeld was invited to a Left Handed Convention to conduct a seminar about left-handedness. He prepares his speech and arrives at the gig but to his horror the place is empty, nobody is there. In a panic, thinking he has gone to the wrong gig he finds a security guard and asks:

Seinfeld: "Excuse me, is this the Left Handed Convention?"

Security Guard: "Yes sir, this is the Left Handed Convention, don't worry you're in the right place"

Seinfeld: "But I'm meant to be delivering a speech to nearly a thousand people in about ten minutes and the place is empty, what happened to everyone?"

Security Guard: "They left"