If you're interested in someone romantically, you might flirt with them, which means to chat them up or tease them in a playful way.
Flirting is an indirect and fun way to let your crush know you're interested, like a seductive line or a few coy words. Or if there's a girl you've had your eye on, you might make a point of walking by her desk and saying hello every morning. But even if you don't have a love interest, you can still flirt. Driving carelessly is flirting with disaster: it's almost like you're toying with the idea of getting into an accident.