We have that problem, but to be fair, he is the singer, so we just let him get away with it.
I often get that -- i have IEMs, I really can't here, and odds on I don't care. And TBH, even without IEMs my hearing isn't great for drunk audience members in the middle of a song.
But the worst thing, in this little bar, this woman who had insisted on standing right to the side of me where I had been having to lean backwards to not hit her with the bass (and failed to avoid her a couple of times), she had wandered off, then came back later and yelled something in the middle a song I was both singing and playing bass to, so I ignored her, then she tried again in the instrumental part, so I yelled I couldn't hear her as I had earphones in, so she went behind me and pulled my earphone out of my ear to tell me that the woman the other side of the bar had been nasty to her.
I am sure it wasn't anywhere near as nasty as I got at that.
I have never heard that expression before in my life, if someone said that to me I would just be looking at them blankly wondering what they meant!