Your shirt is a total giveaway.
Do you ever go up to shake somebody's hand and they slip you something with a funky twist? Not one of those fishy, limp, 'I almost missed your hand' handshakes ... no, one of those firm but weird ones. Then you realize it was a secret handshake from a member of a secret society group. Something you said or did led your handshaker to believe you were a part of his underground troupe. Ahhh, duh, it was the Altamont Secret Society T-Shirt.