what happens in Vegas stays in Vegas

Any scandalous activities that happen when one travels in a group are not to be discussed with other people afterward. The phrase can also be used simply to emphasize that something needs to be kept secret. An allusion to the former advertising slogan of Las Vegas, Nevada ("What Happens Here, Stays Here"), a popular vacation destination with a reputation for hedonism). Primarily heard in US. A: "Guys, please don't tell my wife what happened while we were on vacation." B: "Sure, man—what happens in Vegas stays in Vegas!" I really want this party to be a surprise, so please don't share the details we discussed here with anyone else—what happens in Vegas stays in Vegas, OK?