beneath (one's) dignity
Said of an action that one deems inappropriate and thus would not do. Screaming at someone in public is beneath my dignity, but it sounds like not everyone feels the same way.
beˌneath somebody’s ˈdignity
(often ironic) seeming so unimportant or unpleasant that somebody thinks they are too important to do it: She considers it beneath her dignity to help with the housework now and again.