The word "poop". It sounds so disgusting and I can't bear it if anyone over 6 years of age uses it. Say shit or crap or manure or even stool, just not that stupid nauseating word.
I'm a non native speaker and I honestly thought poop was almost like baby speak for excrement. Hell, it even sounds cute. See also: boop. Have I been wrong all along, or is it just your own perspective?