the word is 'bandied' and the expression is 'bandied about', though I guess 'bandied around' is a variation on this.
It means 'to pass on or discuss an idea or rumor in a casual way'
'backside' would not be regarded as vulgar. It is colloquial, as in " Come on, get off your backside and give me a hand to finish this."
It is milder than the American expression, " Get off ya ass."