Stupid ass washing machine...
I really do think it is just luck.
Perhaps it's Cortana's way with you xD
I got mine by simply going for the Splazer every match I could and doing my best to line up shots.
It's just a mix of chance, luck and skill, I'm afraid.
That said, you could just ask nicely in the lobby beforehand if you're totally desperate. I had to do that for Mongoose Mowdown.
Hope you get it! :)
-Twiggy