Former American Idol judge Steven Tyler took to the mean streets of Los Angeles on this slime green, three-wheeled bad boy.

The Aerosmith frontman was decked out in a ruffled pirate blouse, embroidered leather pants and riding goggles as we spotted him leaving a sushi dinner at Matsuhisa in West Hollywood.

And it was all fun and games until one videographer (not from X17!) started to upset the rocker ...

Tyler grabs the paparazzo's video camera, introduces him as an "asshole" and slaps his hand. When the guy insists on asking questions, Tyler says to him, "Ask my why I carry a knife ... 'Cuz I'm going to a party!" Tyler then pulls a knife out of his belt! Luckily for the paparazzo, Tyler puts the knife back in it's holster and leaves Matsuhisa on his custom Indian Larry "Rat Fink" motorcycle.