STCP (Snooty TCP, "stuckup") is an extension to TCP that introduces regular ping/pong cycles. This wastes a lot of bandwidth, but it allows sockets to know within N ms that packets are currently being lost. Ideally it would be implemented at the operating system level, and the operating system would define a few new signals that would be emitted when heatbeat packets suddenly stop being acknowledged, regardless of whether the userspace program was actually sending/listening for data at that moment.
It's pronounced "stuckup" because any program that monitors its own latency at the expense of everyone's bandwidth must be fairly snooty. Oh, and also so that people may misread it as SCTP and get totally confused, just as a guarantee that it'll never actually be taken any more seriously than it ought to be.