Sling-Shot Wink
When you send a "wink" on match.com (a way to reach out and let someone know you're interested) and the other party winks back instead of sending you an email reply. Now you have to write an email which you may as well have done from the start.
I sent a girl a wink to let her know I was interested. Rather than reply with an email I got a sling-shot wink back from her.