Where did ChaCha20 and Salsa20 stream ciphers get their names from?
idle speculation, my personal favourite! i always thought it was after the dance... 

Salsa dance - see the video (Video demonstrating salsa dancing fundamentals) and jump to ~1min05sec in, the section titled: "side-side-quarter-turns", if you'd prefer to remain seated...

and from (https://en.wikipedia.org/wiki/Salsa20), The Salsa quarter-round function. Four parallel copies make a round.