" It’s called Miss Moxxi’s Good Touch, and you can get it by leaving up to $15,000 in tips in Mad Moxxi’s tip jar at her bar. In addition to that, she’ll also give you Miss Moxxi’s Bad Touch. To truly experience what the gun has to offer, you’ll need to have a controller plugged in if you’re playing the game on the PC. With the Good Touch equipped, the controller with vibrate at a low level even when you’re not firing it.
The fun part happens when you zoom in and out—it’ll vibrate much harder. Have fun with that."