Acronym for Unofficial Patch: a series of bug fixes, texture adjustments and just general gameplay tweaks to games that are publicly modifiable. These patches are not offered with retail copies of the game, and U.P.'s are usually made by skilled game modders or modding projects/collaborations, and not the game developer itself.
A spinoff of the term "A.I." or Artificial Intelligence, a "U.P.I." or User-Provisioned Intelligence" is any user-configured, programmatic entity with the capacity to perform tasks like its specific user would. This might include any of the visual, linguistic, behavioral, or decision-making operations an A.I. would perform, but done in a way characteristically identical to the manner of the user being emulated.
A U.P.I. might be a robot you teach to wash and fold your laundry exactly the way you like it, or a piece of software you train to respond to your emails.
Jennifer's intelligent doorbell was equipped with U.P.I., so as I pressed its sleek, glowing button, it quipped back at me in an all too Jenny-like sardonic tone, "Wait.”