Anecdotally, I don't use a ton of mobile social apps, and the first time I encountered this icon I thought it was some weird play on an equals sign. Never occurred to me it was a menu. Now my own dev team is using it and for some bizarre reason I cannot convince them to stop.
http://exisweb.net/menu-eats-hamburger and followup http://exisweb.net/mobile-menu-abtest
http://conversionxl.com/testing-hamburger-icon-revenue/
http://thenextweb.com/dd/2014/04/08/ux-designers-side-drawer...
http://www.adammcfarland.com/2013/10/24/responsive-mobile-ui...
Anecdotally, I don't use a ton of mobile social apps, and the first time I encountered this icon I thought it was some weird play on an equals sign. Never occurred to me it was a menu. Now my own dev team is using it and for some bizarre reason I cannot convince them to stop.