Falling out of my arse
Similar to "hanging out of my arse" but usually referencing tireness and fatigue instead of a hangover or a sense of feeling ill.
Steve: you gaming tonight?
Mickie luv: nah pal, I'm falling out of my arse, gonna call it a night.
Mickie luv: nah pal, I'm falling out of my arse, gonna call it a night.