Reciprocal flirtation with a girl or guy, signaling a mutual interest in taking things up a notch.
1. There were so many cute girls that seemed interested in me at the party, but I suck
at the flirtback. I went home alone.
2. I got the flirtback from her last night, so I'm definitely asking her out!
3. Dude, she was all over you're ass, gotta step up your flirtback!!