(warning: infectious meme)
The idea that Elvis is so engrained into American Culture that it's impossible to go 24 hours without an Elvis Reference. (Addendum: that assumes that you're within a few devs of the norm on media exposure, or that you talk about american culture.)
You might ask, "What constitutes an Elvis Reference?" And you might try to rationalize what is and is not a reference. The horrible truth is that you'll know--it's a personal thing. Sideburns might do it for you. White bell bottoms might do it. Blue suede shoes. Suede shoes. Blue shoes, suede or otherwise. The word pelvis might do it. An improper reference, or a mistaken reference (say, for example "buddy holly") would nevertheless remind you of the dreaded "elvis".
In the darkest days of the elvis reference, telephone calls were placed, just after midnight, just to say the word. (And yes, the self-referential elvis reference / recursive reference is still an elvis reference.