The "-P Convention" or "P Question" refers to the act of making a statement into a question by appending "P." When spoken aloud, the "P" is literally pronounced as a separate syllable "Pee."

This practice originated among users of the Lisp programming language

Lisp programming language

Lisp is a family of computer programming languages with a long history and a distinctive, fully parenthesized syntax. Originally specified in 1958, Lisp is the second-oldest high-level programming language in widespread use today; only Fortran is older...

, in which there is
the convention of appending the letter "P" on elements to denote a predicate (a yes or no question). It is most commonly used at MIT and the University of California, Berkeley

University of California, Berkeley

The University of California, Berkeley , is a teaching and research university established in 1868 and located in Berkeley, California, USA...

, or among computer scientists working in Artificial intelligence

Artificial intelligence

Artificial intelligence is the intelligence of machines and the branch of computer science that aims to create it. AI textbooks define the field as "the study and design of intelligent agents" where an intelligent agent is a system that perceives its environment and takes actions that maximize its...

 (which frequently uses Lisp).

This usage was immortalized in the Jargon File

Jargon File

The Jargon File is a glossary of computer programmer slang. The original Jargon File was a collection of terms from technical cultures such as the MIT AI Lab, the Stanford AI Lab and others of the old ARPANET AI/LISP/PDP-10 communities, including Bolt, Beranek and Newman, Carnegie Mellon...

 and from there the use spread to some younger users seeking to be part of the classical Internet

Internet

The Internet is a global system of interconnected computer networks that use the standard Internet protocol suite to serve billions of users worldwide...

community.

The typical example of use is:
Q: "Foodp?" (Do you want food?)
A: "T!" (Literally, True: yes)
A: "Nil." (Also Null; no, I don't want food).