Here are some ideas:
It's an idiom.
Nothing - it looks like some kind of abbreviation instead of an idiom.
i think its an idiom, but i think the saying is "You lucky duck"
It emphasizes uniqueness.
youre gay forevee
the kind that swim with sharks
a wart? depends on what kind youre referring to.
youre moms cells
lt depends on what kind of kit you have and what genre of music youre playing
idiom
"Głowa ryby", if what you write is not a kind of an idiom
happy and upbeat music