This one's for Merchant Ships, wherever your members may be -- lost at sea, in Davy Jones' Locker, scattered to the four winds, playing in awesome new bands, quietly reblogging cat pictures while your Tumblr account is besieged by messages from desperate fans, etc.
"Yert" apparently hails from Tennessee, though whether it originated in that cool/pretty okay town or that horrible town that people only defend as a result of a misguided sense of hometown pride remains the subject of heated debate. Many attribute it to Sparta, TN, though it is uncertain which category the town falls into, or White County in general, of which Sparta is the county seat. Its meaning is even more difficult to pin down (don't even bother looking it up on Urban Dictionary), but it seems it is mostly regarded as a greeting or an expression of approval, similar to the juggalos' "whoop whoop" (if you are unfamiliar with either juggalos or "whoop whoop"...Google at your own peril, and may God have mercy on your soul).
I like it! It is almost onomatopoeic. I mean, maybe it is an onomatopoeia, given its mysterious origins...but what sort of creature says "yert"? I suppose we shouldn't worry, though; it is no doubt a friendly one.