Used in Ylvis brother's video "The Cabin". Derives from the norwegian saying "det finnes ikke dårlig vær, bare dårlig _klær_". This saying has a rhyme to it, so when they sang it in english they made up the word kleather to make it rhyme.
Klerton is usually a person who dresses like he's in his 40's, plays the piano, refuses to cut his long hair, likes parrots and is a great friend who makes you laugh.(Keep him tight, he gives good hugs)