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.
"Dude, I think somebody's moon-dogging around here."
"How about a spot of moondogging?"
"Moondogging is awesome fun!"