Obscenity (8)
I believe the answer is:
ribaldry
'obscenity' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for ribaldry that I've seen before include "Coarse jesting" , "Coarse humorous talk" , "Vulgar and disrespectful humour" , "Coarse and disrespectful humour" , "Obscene language" .)