There are a lot of sayings that came from old days, like "bite the bullet". During times of war and fighting, the field medics or your buddy didn't carry anesthetics to ease the pain and just dug out the bullet, stitched up a knife wound, or treated broken bones with out any thing for the pain except maybe some whisky and bullet to bite on so you wouldn't scream.
When I was boy, my neighbor accidentally peppered me with shot when trying to bag a cottontail for supper. When the doc dug them out of my shoulder with only a rolled up cloth to bite on It was a burning pain but bearable. Maybe since that area was fairly soft, but when he started digging into my heel, that was a different story. Back in those days, they wouldn't waste any anesthetics on such a simple thing like that, especially on a kid my age.
Another saying is, "being caught red handed". I guess if you really think about it, you could figure out that it means being caught with blood on your hands, which back then would have been from illegally butchering someone's livestock. Now-a-days one meaning is causing the death or injury to someone.
Just one more. How about "waking up on the wrong side of the bed"? It now means waking up in a bad mood but way back when, the left side of the body (or anything to do with the left) was thought of as evil. So sleeping on the left side (the wrong) side of the bed was considered sinister. Innkeepers made sure the left side of all beds where pushed against a wall, therefore the guests had no choice but to get up on the right side of the bed.
Now tell me, which is the right and the left side of a bed? If you are standing at the foot looking at a bed, the left would be a different side than if you were laying on your back in the same bed. Dang, sometimes life is just so very confusing. . . . Now, I hope you all woke up on the right side of the bed and make sure you have a great day, you hear?