This was a term used by the British music weekly NME in the 1970s and it meant exciting new news and was used ironically rather than as hip slang. As poop is an American word I wondered if they’d got it from Rolling Stone, Creem, Village Voice, etc. or if it was once used by someone like Walter Winchell.

Googling reveals it is a Frank Zappa song with no relevance to the NME sense that I can see.

However, the free online dictionary has

poop 3 (pp)
n. Slang
Inside information: She gave me all the poop on the company party.
[Origin unknown .]

But why poop? I’ve read sentences like “He had all the shit on Nixon” so maybe it is an euphemism.

The OED has “origin uncertain” but then offers the following:

Apparently originally a term from the U.S. Military Academy at West Point. The source cited in quot 1911 also records earlier uses as a verb:
1904 Howitzer (U.S. Mil. Acad.) 221 Poop, to spec blind; to memorize completely.
1908 Howitzer (U.S. Mil. Acad.) 325 Poop, to be able to quote verbatim.
For a suggestion about the word’s origin compare:
1956 M. M. Boatner Mil. Customs & Trad. 121 Poop, information of any sort, usually written (on a ‘poop sheet’). Of West Point origin, probably from the fact that the cadet adjutant makes important announcments in the mess hall from a balcony known as the ‘poop deck’ (from its resemblance to a ship’s poop deck).

Note that the 1956 quote is not OED’s speculation, but since they quote it they must in some sense favor it.

1911 Howitzer (U.S. Mil. Acad.) 227/1 Poop, a speech; a thing to be memorized.

But etymonline has:

poop (n.3)
“up to date information,” 1941, in poop sheet, Army slang, of unknown origin, perhaps from poop (n.2).

perhaps from poop (n.1).

The stern of a ship.

NME probably got it from Billboard, which used it similarly; for instance, from the Jan. 20, 1973 issue: “Proverbial Hot Poop: This past year has seen an increase in stellar sessions, with the Sahm sessions receiving the most recent splash. Now rumor reaches us of yet another marriage of the powers, this time centering around Barry Goldberg...” It’s on page 16, second column from the right (for those who can see it).

The difference between etymonline and the OED is one of date. The OED entry is relatively recent (2006). The second edition entry gives a 1941 date (as does every other slang dictionary I consult, including the very recent Green’s). Harper is relying on the second edition.

So it looks like the OED is the best source on this one.

As to the 1956 explanation, I wouldn’t say the OED favors it. The editors use the words “suggestion” and “compare.” I interpret this as them saying the explanation is plausible and from an authoritative source, but speculative.

The CANOE based theory is interesting—kind of a modern alternative to scuttlebutt.

If you google “West Point” and “poop deck” you get a number of hits—including a West Point related blog with a title something like “news from the poop deck” and photos of a panoramic view from the poop deck at West Point.

No explanation of why West Point would use a term from the Navy.

I’m wondering if the West Point poop deck comes from poop = info and not vice versa. It is a balcony overlooking the mess hall from which announcements are made.