It comes from Bulgarian, It's used to answer something you don't want to give the answer to. This is a litteral translation of the phrase.

Note: It's very childish to say something like that, It's like using the phrase "no u", one of the reasons It's used is because It rhymes.
Some Guy: Why won't you ever answer any question with an actual answer?
Other Guy: It's Because why, "why" ends on a "Y"
by UglyFatBoy98 April 29, 2020
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