The act of stealing a sip of somebody's drink (usually when they are not looking). Usually employed by those who are unemployed.
There are many levels of moon dogging, and beginners should be careful when practicing the more advanced techniques.
Level 1 - The Basic Moon Dog: Stealing a sip of a drink from somebody while in plain sight.
Level 2 - The Proper Moon Dog: Stealing a sip of a drink from somebody while their back is turned or while they are distracted. Beginners usually perform this in teams of two.
Level 3 - The Full Moon Dog: Stealing somebody's entire drink while they aren't looking. The moon-dogger usually moves to the other end of the bar at this point to finish the drink out of the mark's view.
Level 4 - The Moon Coon: Stealing somebody's entire drink and passing it on to somebody else. The recipient of the drink doesn't necessarily have to know that he or she is drinking a stolen beverage. Hilarity usually ensues.
"Holy shit! Where's my drink?"
"Dude, I think somebody's moon-dogging around here."