french expression, means weird, suspicious, strange
born from "verlan" french slang that switch parts of some words like "maison" becomes "son-mai"
"chelou" comes from "louche"
The word "touché" is also often used in popular culture and general conversation — for example, in an argument or debate — to commend someone on a clever response to an argument. The thank the person for commending you on your cleverness the correct response is to say "chétou"