Assuming the cops won't be sympathetic and there's no cameras in the men's room, dump the contents in the furthest stall you can find, without touching any of it. Then get the hell out of there on the first flight back you can get or head to the embassy.
What would be the incentive for killing the guy, though? Since nobody knows who the criminals are, sending a message "don't mess with - uh, nevermind" isn't very useful?
True, though violent criminals aren't always known for being driven by pure rationality and avoiding emotional outbursts, and drug trade is probably run by such criminals.
