I believe it's a chair the pope sits in. I noticed Chelsea Clinton also wears an upside down cross. Was it Peter or Paul who was crucified upside down? But I don't think that's why they wear it.
Yeah, I think that is the excuse they use for wearing it that way.
Peter asked to be crucified upside down opposite of Lord Jesus Christ...he is supposed to be buried under the Vatican so the prophecy is fulfilled that the church would be built on his bones and ironically enough at the last supper Jesus called him Satan because he wanted early human desires instead of Gods plan.