be in and out

1. To go into some place and complete one's business there very quickly or efficiently. Don't worry, I'll be in and out—I just have to get some cash from the ATM. Please? We'll be in and out—it'll only take five minutes. A: "Wow, you were in and out quick." B: "Yeah, well, I only had to get toothpaste."

2. To alternate between being at or in a location and being gone from it. The boss has been in and out of the office all day. The kids are in and out so much that they're constantly letting bugs into the house. Mom's been in and out all day, but she said she'd be home for dinner.