Dublin knackers mating call to each other, often let out in a loud screach, much like a seagull. Often used as a back up call to fellow inmates or 'budz' when starting fights or 'scraps'. When used by professionals can only be heard by members of the same herd or 'gang' as it is too highpitched to be heard by regular ears (akin to dog whistles).
Lazzo: "Schwear ladzzz, they're schtartin' budz!"
Davo: "we're comin' Lazzo, we're comin'! SCHWEAARRRRRRRRR!"