i have see this film many time and i like all bad teacher want to give it ten out of ten but feel that it would be unfair to other good film . however and i do think that this be one of those rare gem represent a perfect comedy . it be i would venture one of the great comic film of all time . matthau and lemmon be perfectly match and mismatch . the script be so sharp that you need to staunch the bleeding . the story be well know and have already be describe in other comment . the two lead give extraordinary performance and the girl be superb and the situation be side splittingly funny . not one swear word in sight ( mark that hollywood and you do not have to swear to be funny and you have to be witty ) and the move from stage to film be seamless . they do not makeem like this any more . timeless .