The word gypped comes from gypsy, but gypsum does not. Gypsy, considered a slur by the Roma people, has an origin that reflects the uneducated bias against them. In Middle English, it had alterations ranging from gipsy to gypcyan to gipcyan. All of this derives from the Old French word gyptien, which was a shortening of egyptien, meaning "Egyptian". This is a misnomer; people incorrectly believed that the often-darker-skinned traveling groups came from Egypt. The clipping process of losing the e is quite common in English, and there are many similar examples. Egyptien derives from the Latin aegyptius, from the Greek aiguptios, which, unsurprisingly, is likely Egyptian in origin. It is believed that the word traces to hwt ka pth, a phrase meaning "the temple of Ptah's soul", but that's unconfirmed. If so, the roots are clearly Semitic and come from another unintelligible spelling, for sure.
Adam Aleksic, a rising sophomore studying linguistics and government at Harvard University, has been described as the internet's sixth most famous etymologist. He also has disturbing interests in politics, vexillology, geography, board games, conlanging, and law.