Definition of "IOI"

If she asks you what your name is, that's an IOI. If she asks you if you're single, that's an IOI. If you take her hands and squeeze them, and she squeezes back, that's an IOI. And as soon as I get three IOIs, I phase-shift.

2005, Neil Strauss, quoting Erik von Markovik, The Game: Penetrating the Secret Society of Pickup Artists, Text Publishing Company, page 151

She gives you a fake IOI to see if you will start chasing her.

2007 February 6, Erik von Markovik, The Mystery Method: How to Get Beautiful Women Into Bed‎, St. Martin's Press, page 129

Pickup artists must continually gauge their reactions, seeking IOI, or “indicators of interest” from the opposite sex.

2008, Faye Flam, The Score: How the Quest for Sex Has Shaped the Modern Man, Penguin Group, page 32