To masturebate in someone else's house; or someone else's property. In many countries this is a sign of deepest gratitude to your host, but it is best advised to check with a local before starting up your engines. This is different from public masturbation.
A communist that actually is not a dick (like the winning majority in history have been), thinks you can only have communism if it is based purely on rational human self-interest and desire, and would rather not have a revolution at all than have one that leads to something worse than you started with. A person who wants communism without MarxISM or any other "persons-name-ism".