A sexual act performed when a male, while having sex with a female in either the missionary or more preferably the doggy style position, reaches around his backside and obtains a sizeable amount of sweat from his Perineum (a.k.a. Chode, Brum, Taint, etc.). Said sweat is then wiped upon the females upper lip, directly underneath the nose. The maneuver is completed with the male folding each of his arms to resemble wings, flapping his "wings", and vocalizing an ear-shattering "Quack-Quack".
As Brian was ravishing Krista from the rear and giving her the ultimate in sexual pleasure, Krista suddenly felt Brians finger on her upper lip. Within an instant her olfactory senses were overwhelmed by an extremely foul odor, accompanied by the loud call of the Mallard Duck and a rush of air upon her backside presumably caused by the flapping of limbs. Unbeknownst to Krista, she had received the ultimate sexual insult: The Dirty Mallard!
When some resigns or retires from a job, they are on "eternity leave". This can also refer to someone who has passed away, especially someone who worked somewhere for a long time, retired/resigned, then passed away later.
Oh I'm sorry, you didn't know that Kelly is on eternity leave? She resigned and moved to Hawaii!
With regrets I would like to inform you that my boss is officially on eternity leave. I will never see or hear them again. Ever.
The hypothetical man (often a sinistercharacter who decided not to go to boot camp) that is doing your girlfriend/wife while you are on deployment overseas.
Ain't no use in goin home,
Jody's got your girl and gone.
Ain't no use in goin back,
Jody's got your Cadillac,
Ain't no use in feeling blue,
Jody's took your checkbook too.