The process of producing a piece of work which, while boasting little content, manages to dazzle the viewer with a seemingly impressive display of intellectual girth.

(Opinion) Art forms such as Dada (anti-art) are a form of Pseudo-Intellectual Masturbation. It is important to note that, if a work of art has little content or has been produced with little thought about the meaning, etc(the first sign of PIM), it is not neccessarily PIM! Art can also be meaningful, spiritual, whatever, by being aesthetically pleasing instead of having something important to say.
PMI can also occur in other fields: literature, home gardening, and even sometimes science. So, I have set up a few criteria for PIM-detection to be used daily.

1. The work must give a considerable amount of glorious credit to the author (if it's anonymous, it will not bring glory to the author. Therefore, it really can't be very masturbatory, eh?)
2. The work may not contain any insightful thinking, meaningful remarks, or thought-provoking ideas. (Who here understands what a door frame standing on its own in the middle of the room tries to convey to the viewer? The answer is simple: PIM)
3. The author must claim that the work has important value in the context that it is set in. I.e. if the author says its crap, then it is just published crap.
4. The work itself must be reminiscent of real, important, imaginative work. (Dada is crazy like most modern art, right?)
and..finally,
5. The work has been produced with little thought or effort.
Farewell, and good night.