Chicken shit. We're not talking here about the slang term used by our American brethren for those of a cowardly disposition, but the real thing. Gen-u-wine, 100%, echt, merde de poule. The stuff has many uses, fertiliser and, er, fertiliser being just two of them. But for all its undoubted versatility, the guano of your average rooster is generally recognised as being a Bad Thing for Beer.