It's the nickname my friend gave my WRX when I took a series of curves faster than he thought physically possible! I think it was in the wet too. --> AWD=GRIP. Although I never used the name on the Subaru forums, it was the first handle I tried that wasn't taken when I started reading the Bimmer boards.
Oh, and it's nothing to do with Kermit. He's just there because he's one of my lifelong heroes.