Moxxi’s Bad Touch is her second favorite gun and is an extremely powerful variant of the Maliwan Venom submachine gun. You can only get 1 reward each time you enter Sanctuary. After that, you will always receive Moxxi’s Good Touch. The first reward is always Moxxi’s Bad Touch which can only be obtained once. Therefore, it is possible you can get these items cheap or very expensive. There isn’t a set amount of money you need to give as it is randomly triggered.
Moxxi can give you one of two rewards by tipping her. Moxxi’s Tipping Jar Returns in Borderlands 3 MentalMars Moxxi’s Tip Jar Rewards
Inside the bar you can find a tipping jar but what happens if you give her money? Well, Gearbox Software actually has hidden 2 weapons in the game that you will receive if you tip Moxxi. You can find Moxxi’s Bar in Sanctuary, the main hub town of Borderlands 2.