I was watching "Casualties of War" today.

One of the characters, a soldier, interrogates a suspected VC (Viet-Cong) old man by asking him "Are you VC? Number fucking ten?"

Is "number fucking 10" some kind of military slang, or maybe is it some mnemonic way to ask something in Vietnamese?

  • 2
    I thought it was because Raining blood from slayer's "Reign in Blood " is track number 10. Now you've ruined it for me. Aug 18, 2016 at 14:17

4 Answers 4


A quick online research shows that "number 10" is indeed part of 60s' Vietnam War jargon, meaning "the worst" and being the opposite of "Number 1": "the best"; according to glossaries in Ray's Web Server and Institute for Advanced Technology in the Humanities of Virginia.

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    And in case it's not obvious, "fucking" doesn't have any extra meaning here and is just a case of swearing to add emphasis. Aug 18, 2016 at 12:15
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    @MaxWilliams Specifically for a site about language, it is an intensifier. Aug 18, 2016 at 14:49
  • It's also worth noting that Koreans will still use this terminology today. They've said, "You number 10, G.I." to my dad while he was still in the military (where G.I. is slang for a Soldier, standing for Government Issue)
    – Erin L
    Aug 19, 2016 at 15:39
  • Hence Number 11 is worse than worst?
    – adib
    Feb 6, 2019 at 4:20

I think, in the context given in the question, it means American in a pejorative sense (see @armen-Ծիրունյան's answer), with partial rhyming slang (ten/-can).

The interrogator already thinks the guy is VC, and is using language to try to get him to admit that. If the guy balks at the pejorative term, then that's more of an indication that he sides with the Americans than just simply agreeing to the pejorative term.

This analysis of the "poem" suggests it refers to Americans who raped / made Asian women pregnant:

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This glossary also suggests American:

enter image description here

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    In the OP's question, it's being applied to someone suspected of being VC, so not likely an American. The common American phrase "number one" came to mean "good/best" in Vietnamese English dialect; "number 10" is the necessary contrastive to mean "bad/worst". Aug 18, 2016 at 13:57
  • @RussellBorogove On the contrary, I think it's perfectly correct: He's asking whether the person supports the VC or Americans, which makes perfect sense (to me) in the context.
    – Peter K.
    Aug 18, 2016 at 13:58
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    If you're a supporter of Americans, you don't use a pejorative term for them, which "number 10" clearly is in "Number fucking ten cheap charlie GI cocksucker". Likewise a soldier interrogating a suspected VC, being either American or South Vietnamese, doesn't associate "number 10" with Americans. Aug 18, 2016 at 14:05

The insertion of "f*cking" into the word is an intensifier.

The practice is called "expletive infixation." https://en.wikipedia.org/wiki/Expletive_infixation


It is a term used largely in the Vietnam War. 1 is the best, 10 is the worst. As stated above, the obscenity thrown in just intensifies the meaning behind it. Nothing to do with slayer or a poem in 1975 as it was used as a negative term (slur) aimed at the Americans and Australians in the Vietnam war. It pre-dates the 1975 poem (Unless the poet got their inspiration from the Vietnam war).

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    Hi Dave, welcome to EL&U. I'm struggling to see how this adds anything to our site: it looks like a recapitulation of the main point in the accepted answer, plus your personal commentary on the relevance of some other answers. It would have been better as a comment. PS what is the reference to "slayer"? Feb 6, 2019 at 4:18

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