A lot of dialectical words are actually just taboo renditions of common words.
旺子 [wang zi] in Sichuanese comes from taboo on saying the ominous, inauspicious word blood 血 and probably morphed from the actual character 衁.
Obviously blood 血 could have been used and could have been said but out of taboo a new "word" was created.
I found one in 汉语大词典:
I would imagine that 死 isn't as taboo as it used to be though.
What common MSM words now are the result of taboo?