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.
beneath one's dignity
too rude or coarse for a polite person to do. That kind of thing is beneath my dignity, and I hope yours as well. I would have thought something like that to be beneath your dignity.
beneath your dignity
of too little importance or value for you to do it. The Latin equivalent is infra dignitatem , and the humorous abbreviation of this, infra dig , is sometimes used in informal contexts.
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.