The origins of this phrase are unknown but it's commonly used to convey being screwed up the fundament in a 'straight in, no kissin' kind of way - whether the recipient wants it or not.
It's expected that wage earners will be taking an astral in the forthcoming budget."
"Dublin footballers were upset at taking an astral from Cork last Sunday."
"That poor guy will be taking an astral for charity at Beatrix's party next Sat.".