I admittedly don't get the joke behind that, either.
Maybe because I'm not insane enough to get it, yet.
The sounds of waves crashed near the shore and a lone girl stood alone, practicing her fighting skills against a fully-animated human dummy made of water. Switchblades in hand, she made her mark almost every time. The last time, however, was a miss that got her send back flying.
"Great, I'm being kicked by a creature I made with my own Hydrokinesis," she muttered before getting back up on her feet, returning the dummy to the ocean.