Sodom and Gomorrah ... giving themselves over to fornication, and going after strange flesh, are set forth for an example, suffering the vengeance of eternal fire. 1:7
Trivia: What did the devil and Michael the archangel argue about, according to Jude 9?
God sent "eternal fire" on the people of Sodom and Gomorrah for "going after strange flesh."
7-8
A note about the "strange flesh" of Jude 7