It’s probably some derivative of the maratime slang pipe-down.

Pipe down: A boatswain or ‘bosun’ was a ship’s officer who was, amongst other duties, in charge of the crew. He would issue different orders to crew members by changing the sound patterns blown on his ‘call’, a sort of high-pitched whistle.

‘Pipe down’ was the last order of the day for off-duty crew to stop talking, settle down or go to bed. Today, the phrase ‘pipe down’ is still used to tell someone to be quiet.

If an officer is piping orders the expectation would be for you to pay attention.

The second world war and its huge naval population probably brought the much older term into American slang.

I SAID I WILL NOT BE TAKING ANY QUESTIONS AT THIS TIME.

It is in computer programming terms.

Also in the ‘pipe down’ (shut up) sense