The beautiful sack on the neck of a bird, can be a literal sack such as frigate birds and marabou storks, or feathers, such as a ravens hackles, or a tui's neck feathers.
Oh Joshua, I'd love to go stroke a big hairy birdsack one day! Wont you come with?
Why yes Emily my dear, I'd love to play with some birdsacks. Let's go to the Raven Aviary to play with their Big Black Bushy Birdsacks.
Disparaging nickname of rapper Brian "Birdman" "Baby" Williams. It implies that Birdman does, in fact, suck. Songs by other, more reputable artists in which Birdman makes a guest appearance are often labeled as "featuring Birdsuck."
To take or attempt to take a Bird scooter from another person by use of force, intimidation or by taking parked scooter without another Bird within half mile.