From Longman Dictionary of Contemporary Englishoff colouroff coloura) [not before noun] British EnglishILL someone who is off colour is feeling slightly ill b) [usually before noun] especially American EnglishRUDE/OBSCENE off-colour jokes, stories etc are rude and often about sex → colour
Examples from the Corpus
off colour• I'm fine, thank you, but Elinor's a bit off colour at the moment.• Bruce went to the doctor, feeling a little off colour, and was told that he had anaemia.off-colourˌoff-ˈcolour British English, off-color American English adjective 1 RUDE/OBSCENEsexually offensive off-color jokes2 [not before noun] British EnglishMIILL slightly ill She’s been feeling a bit off-colour lately.Examples from the Corpus
off-colour• How does a rat tell the experimenter that it has a headache or feels a bit off-colour?• And you're looking a bit off-colour, to be honest. 