The garbled sound you make when you don't know the answer to something or your not sure what you're talking about and is used in conjunction with clearing one's throat.
1. Reflexive Russian verb, loosely translatable to English as "I resign" or "I give up", usually used in conjunction with President Donald J. Trump's Twitter feed.
2. American verb, early twenty-first century origin. Possibly from the aforementioned Russian verb. Used to mean "Facepalm" or "Good God, what have we done?/What have we elected?"
Russian Verb: Putin's Aide: Comrade, perhaps it is time we accepted that President Trump needs to covefefe.
Putin: What? After all the work we spent trying to get him elected? Twelve years in the gulags!
American Lexicon: Stephen Colbert: Thanks to Russia, we have elected a giant, massive, covfefe of an imbecile.