be on the prowl

1. To be actively and perhaps aggressively seeking a sexual partner, especially during a certain situation or in a certain setting. This bar is a favorite of older women who are on the prowl. Let's get out of here—most of the guys at the bar are on the prowl, and it's pretty annoying. I'm single now, yeah, but it's not like I'm on the prowl. I'm still getting over my ex!

2. To be actively searching for someone or something. Usually followed by "for." I've been on the prowl for a new television at a good price. Steer clear of the boss, he's on the prowl for someone to yell at this morning. How do you like your lawn mower? I'm on the prowl for a new one.

be/go on the ˈprowl

1 (of animals) move around quietly while hunting for food: Our cats go on the prowl at night, and then they sleep here all day.
2 (of people) be moving around quietly because you are trying to catch somebody or intending to commit a crime: Look out for burglars on the prowl. If you see anything suspicious, call the police immediately.