said of stories, language, etc: crudely or obscenely humorous
said of a person: inclined to indulge in coarse or indecent humour
Over the mantel was the familiar picture … of a young lady having her shoes shined by a ribald small boy — Christopher Morley
ribaldry /ʹribəldri, ʹrie-/ noun
[Middle English, in the sense ‘menial retainer, rascal’, from Old French ribaut, ribauld wanton, rascal, from riber to be wanton, of Germanic origin]