I hear ya dude,
Personally, I would stay away from the coffee houses. I don't want to be around any guy with a 600mil 5.6 loaded up on caffeine and waving that thing around.
Besides, how much of an intellectual discussion could you have with a guy with a lens like that. I'm thinkin not much.
More than likely he'd just put someones eye out.
I'm doing sensative stuff with my wife this afternoon.