The act of removing ones penis from the anus of a another recently fucked individual, and slapping ones dick across their or anothers face to replicate the dirty sanchez, but in a more demeaning way.
I picked up this mad slut at a club and she asked for something she has never had before, so I gave her a good ole dirty bird!
Whilst standing ontop of the castle in Edinburgh proceed to wank over the edge first person to hit someone below wins if you get caught say it's bird shit
John "Matt got hit by some bird shit"
Stuart "That's not bird shit ,those are some scottish "bird" droppings