Finally I have an expression without multiple potential origins and a very clear linage, it seams to be surprisingly rare in tracing these expressions. I think the only other one that was clear was the very first one "blowing smoke in my ass".

Source

Caught Red Handed, this is an expression we use when we catch someone in the act of committing a crime or a minor offense. It's fitting since I used it today when I told my wife about catching out kids making popcorn while we were playing hide and seek.

Anyways the expression actually started in reference to the exact same thing. Well not making popcorn, but committing a crime back in the early 1400s. Of course the most common crimes then were murder or poaching, both with left the perpetrator with bloody or red hands if they were caught in the act.

Source

The lineage is so clear that it was actaully written in Scottish Law in 1432;

That the offender be taken reid hand, may be persewed, and put to the knawledge of ane Assise, befoir the Barron or Landeslord of the land or ground, quhidder the offender be his tennent, unto quhom the wrang is done or not… And uthers not taken reid hand, to be alwaies persewed befoir the…

Clear right? Is that how they still talk and write in Scotland

To get even clearer the expression was official first written red-handed in the book Ivanhoe by Sir Walter Scott in 1820.

This was probably even an easy one to figure out yourself, if you really need to impress your friends check out a few of the ones below.

If you want to check out any others from my Origin of Expression Series check them out below

Blow Smoke up Your Ass

Son of a Gun

Pass the Buck

Bought the Farm

Dead as a doornail

Mind you P's and Q's

Knock on Wood

Bringing Home the Bacon

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