Ribaldry or blue comedy is humorous entertainment that ranges from bordering on indelicacy to indecency. Blue comedy is also referred to as "bawdiness" or being "bawdy".

Sex is presented in ribald material more for the purpose of poking fun at the foibles and weaknesses that manifest themselves in human sexuality, rather than to present sexual stimulation either overtly or artistically. Also, ribaldry may use sex as a metaphor to illustrate some non-sexual concern, in which case ribaldry borders satire.

Like any humour, ribaldry may be read as conventional or subversive. Ribaldry typically depends on a shared background of sexual conventions and values, and its comedy generally depends on seeing those conventions broken.

The ritual taboo-breaking that is a usual counterpart of ribaldry underlies its controversial nature and explains why ribaldry is sometimes a subject of censorship. Ribaldry, whose usual aim is not "merely" to be sexually stimulating, often does address larger concerns than mere sexual appetite. However, being presented in the form of comedy, these larger concerns may be overlooked by censors.

Ribaldry differs from black comedy in that the latter deals with topics which would normally be considered painful or frightening, whereas ribaldry deals with topics that would only be considered offensive.