i'm watching british cop show about 80's cop. there's a scene where a lot of people are talking at the same time in police station. they are mostly immigrants or visitors from s.africa(i don't know it's relevant or not.). then one cop(A) got up and said and the other cop(B) added.
A: a bit of hush, please. Nobody's falling down any stairs here!
B: i don't know about that.
i don't know why A said "nobody's falling down any stairs" and does it have any idiomatic meaning? or does it mean 'nobody is hurting' or 'nobody is gonna hurt you' kind of way? so don't make a fuss and be quiet?