Attempting to enter Canada with only 2 liter bottle of Mountain Dew, 1 loaf of bread, some peanut butter, and 14 dollars, only to be told that you have insufficient funds to enter Canada.
John Green went John Green-ing once, ended up on a list of undesirables and was told "John Green, you're gonnadie on that list."
Feigning the appearance of being sell-out. Bringin a watered down version of artistry into the mainstream. Also applies in any situation where one is temporarily sacrificing their core tastes/values/talents (Room for squares) in pursuit of greater art/good/reward (JMT Try!, JM w/ BB king, JM w/ ?love). Be warned, one who is John Mayer'ing risks taking a hit to their reputation that may never be overcome.
-See John Mayer
-Also see, Justin Timberlake -Dude its cool, I'm just John Mayer'ing when I watch Desperate Houswives every Sunday night with my girlfriend. I always get sweet sweet lovin after its over.