Term referring to a 'townie', commonly found wearing a Burberry cap, sovereign ring and driving a Saxo, Ka, Corsa, etc with cunt kit. 'Mush' is the noise made by the bass through the super-woofers in their car as it passes. See also chief.
Also a term used to salute a male stranger.
"Alright mush?"
"Fuck off mush, who do you think you are?"
"mush mush mush mush mush" from speakers of passing car.
'Oi mush - fuck off!" - amusing song based on a 'mush' from a West Walestown.