An acronym for the notable alternative rock band In Search of Sasquatch. Formed in 2010, in the one and only Calgary, Alberta. Consists of four young lads and is soon to be the most commercially successful act in the history of music.
Person A: "Did you see ISOS perform today?"
Person B: "No, I missed it. How was ISOS?"
Person A: "Pretty good if you know what I mean"
Person B: "I'm kidding, I did see ISOS perform"