A term that originated and was popularized in Sudbury, Ontario. Short for Down Syndrome, it is used in a less offensive way or when it would be otherwise inappropriate, ie in public. Used as a remark on the general stupidity of someone/something or a recent event.
Guy 1 : Man, Dave is really pissing me off today!
Guy 2 : Why? What did he do?
Guy 1 : He's just being a D.S and it's really annoying.
Bob: Did you see what Liam did at the party last night?