inappropropriate 

adj. used for describing things, such as conversational topics, that are both pertinent to the subject at hand as well as off-colour.

-'I was answering a letter querying what the congressman was going to do about child kidnappings and I was tempted to put in a quote from "Taken".'
-'Good idea, but no, that's completely inappropropriate.'

inappropropriate by Parlez-vous January 11, 2012