"Some days you are the dog, some days you are the tree / fire hydrant" is the canonical quote.
I would assume the fire plug is the name of one of the things that failed while he refueled. Doesn't quite go together in my head, but once you understand the original quote it makes sense. Some days you're on the giving end, some days you're on the receiving end.
Re:I Fell 15,000 Feet and Lived
by techsupporter on Monday October 16, 2017 @10:10AM
(#15483281)
At least where I’m from (Texas, where the story teller at least spent time), hydrants are called fire plugs. I’ve no idea why but that’s what I know them as.
The term comes from the history of firefighting: http://www.firehydrant.org/info/hist-fp.html
“Some days you are the dog and others you are the fire-plug.”