Having a jam session....not sure how "jam" became slang for playihng music or music itself like "kick out the jams"
Here's one I honestly don't know about. Is "calling a spade a spade" a racist term? I could make an argument either way.
I've always assumed it was because a dime is the smallest coin, and the implication is that the pass was so precise that it could hit a dime squarely. Much like the phrase "stop on a dime", meaining the ability to stop almost instantly.
The lowest figure on the totem pole is the most respected though. So, the way it's used is ass backwards. So, they are cold huh...ok
It didn't start out that way. It originally just meant calling out something for what it was, and refered originally to the garden spade. In the 1920's it began to be used to refer to black people and is listed as one of the many slurs against them. It came to refer to the card rather than the garden instrument, and spawned another racist saying, black as a spade. Several black civil rights leaders and poets worked to take it back. So, yes it is a racist term, or at least became one.
Since witches were traditionally burned at the stake, it's fair to say their body parts were hot, not cold.