I know its true because "ok boomer" began as a scripted response used by the paid ShareBlue shills on Reddit in 2015 not long after about 100 of them brigaded the conspiracy forum pushing the fake "piss tape" attack with brand-new accounts made that same day. Most of those brand-new Blueshare shills became permanent fixtures in that sub, and "ok boomer" was one of their favorite phrases of dismissal