The phrase "proverbial elephant" means a well-known and commonly talked about object or topic, similar to an elephant that everyone can see and discuss. Full definition
Scott's «proverbial elephant in the living room» is perhaps too earthbound a metaphor. (slate.com)
«Let's discuss the proverbial elephant in the room — some reports even mentioned you have an armed guard stationed outside your office,» noted Rep. Charlie Dent, R - Pa., during Shulkin's appearance before the House Appropriations Committee. (cnbc.com)
LeEco's founder and CEO Jia Yueting was forced to deliver his keynote with the stubborn FF 91 as a backdrop serving as the proverbial elephant in the room. (techtimes.com)