Pulling a Lipschitz is the act of taking a bath in a stranger's house without them knowing about it. Most commonly performed at a party where you don't really know the hosts. This way there's probably a lot of loud music and distractions, and it will be easier to pull off. The term comes from the Rugrats character Dr. Lipschitz, who is supposed to be babysitting the kids, but instead runs himself a bath.
Also known as "pulling a Danny C."
Person 1: Hey, was that party last night any good?
Person 2: Nah, it was really lame so I tried to pull a Lipschitz. Unfortunately, the girl whose house it was heard me running the water and wasn't too happy about it.
Person 1: Ah man! You'll get it next time.