Quote Originally Posted by diogen_ View Post
I like трын-трава because it forms catchy phrases in several hilarious songs
If I'm not mistaken, трын is a corrupted form of тын, an old word for "a fence" (for which забор is now the usual term).

So тын-трава was "grass that grows by the fence" -- in other words, useless weeds -- and трын-трава was a nonsensical variant.

(But later the meaningless трын-трава was explained as being a "magical fairytale plant." Cf. "schnozzberries" in Willy Wonka's chocolate factory, or Dr. Seuss's "truffula trees".)