The act of pressing ones anus against the vaginal canal of a pregnant female duck. The duck then births an egg into the human's anal cavity without breaking it. If the egg breaks in the process, the act of full mallard is voided.
Once the egg has been completely transferred to the human, he or she may then pass the egg to another human or animal in the same fashion.
"dude, i got kicked out of the petting zoo"
"they caught me going full mallard in the pond area"