Russian Sip
Much like an American Sip, the Russian sip is typically much less about bravado and more often an underhanded way of killing someone's drink. This involves requesting a taste, or sip, of a drink and, upon being handed said cocktail/flask/beer/etc., chugging to its completion.
I was sure to keep my hand on the flask while my friend took a nip off my flask to insure he didn't execute a Russian sip.