like a square tenon for a round mortice (/a round peg in a square hole)—at variance with each other
? 持方枘欲內(nèi)圓鑿，其能入乎？(《史記·孟子荀卿列傳》) How can you fit a square peg into a round hole?
方枘圓鑿圓鑿方枘fānɡ ruì yuán zuò
鑿：榫眼；枘：榫頭。方榫頭插不進(jìn)圓榫眼。比喻不相投合。at variance with each other, like a square tenon for a round mortise, a square handle and round socket