The rudest thing

Context: "What’s the rudest thing you can do at someone else’s house?"

Answer

Voiding your bowels on the dinner table while bellowing Verdi and masturbating.

Timing is critical. You want to get all three processes to climax simultaneously.

PS— It is a given that, in addition to the shitting and bellowing and jacking off, you are also having an affair with the host's spouse(s).

PPS, and you brought your three dogs to the party. They too shit everywhere, and bite and howl.

When the police come, you give them your neighbor's name and ID and slip away.

Now that was a party to remember.