You're at a party and you catch someone giving you a dirty look or talking crap about you. You would reply with "Don't sip." Basically you're saying, "Don't hate on me right now."
A Greek distilledalcoholic beverage, more precisely a pomace brandy that will totally fuck you up and make you sleep with fugly chicks.
Steve: Whoa dude, how the fuck did you manage to bone that fugly chick, you must have had a strong stomach!
Jim: Nah man, just a fuck load of Tsipouro!