1. [Transmission Control Protocol/Internet Protocol] The wide-area-networking protocol that makes the Internet work, and the only one most hackers can speak the name of without laughing or retching. Unlike such allegedly ‘standard’ competitors such as X.25, DECnet, and the ISO 7-layer stack, TCP/IP evolved primarily by actually being used, rather than being handed down from on high by a vendor or a heavily-politicized standards committee. Consequently, it (a) works, (b) actually promotes cheap cross-platform connectivity, and (c) annoys the hell out of corporate and governmental empire-builders everywhere. Hackers value all three of these properties. See creationism.
2. [Amateur Packet Radio] Formerly expanded as “The Crap Phil Is Pushing”. The reference is to Phil Karn, KA9Q, and the context was an ongoing technical/political war between the majority of sites still running AX.25 and the TCP/IP relays. TCP/IP won.