What Beer??? all I saw is knockers.
BTW if any of your wifes drink champaigne (cant stand the stuff) but the wooden corked ones, the cork makes a great knocker and its free with the bottle. I own several ashtrays just for my pipes and I had bought a knocker for one of them and my Dog of all things ate it, yes the DOG ate it, I aint making that up, well anyhow the next day my wife was celebrating something (aniversary or so cant remember, hope she aint looking) and she popped a cork and I saw the wooden cork and though looks just like a knocker, glued it to the ashtray and it works great.