1
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Act on what you are saying or stop talking about it, as in You've been citing evidence for months but never presented it? now put up or shut up. This somewhat impolite term, often put as a command, is believed to come from gambling, in which a card player is told to ante up or withdraw. A second theory maintains that it means either put up your fists to fight or back down. [1870s] Also see PUT ONE'S MONEY WHERE ONE'S MOUTH IS.
American Heritage Idioms
2
general::
Phrase(s): Put up or shut up!
1. Inf. a command to prove something or stop talking about it; Do something or stop promising to do it! • I’m tired of your telling everyone how fast you can run. Now, do it! Put up or shut up! • Now’s your chance to show us that you can run as fast as you can talk. Put up or shut up! 2. Inf. a command to bet money in support of what one advocates. • If you think that your horse is faster than mine, then make a bet. Put up or shut up! • You think you can beat me at cards? Twenty bucks says you’re wrong. Put up or shut up!
McGrawhill's American Idioms And Phrasal Verbs