End of Year Quote

Hey guys, I need a bit of help...

So, I've accidentally got a reputation of being able to speak elvish in School(Sadly, I can't) and, however adamantly I insist I don't, they won't believe me. I thought of a joke I would like as my end of year quote, but, of course, I can't speak Elvish... It's simply the phrase 'I lied, I do speak Elvish' in Elvish. Could someone please translate this for me, please? Feel free to paraphrase that as much as you need so it translates correctly :)

Thank you \o/

I would say: cuptanen, istan quete Quenya

Bear in mind that cupta is a neologism (fan invented word) for “to deceive, lie”, but the rest of the phrase is pretty sound: istan quete Quenya = “I know how to speak Elvish”