ribald (adj.)

c. 1500, from ribald, ribaud (n.), mid-13c., "a rogue, ruffian, rascall, scoundrell, varlet, filthie fellow" [Cotgrave], from Old French ribaut, ribalt "rogue, scoundrel, lewd lover," also as an adjective, "wanton, depraved, dissolute, licentious," of uncertain origin, perhaps (with suffix -ald) from riber "be wanton, sleep around, dally amorously," from a Germanic source (compare Old High German riban "be wanton," literally "to rub," possibly from the common euphemistic use of "rub" words to mean "have sex"), from Proto-Germanic *wribanan, from PIE root *wer- (2) "to turn, bend."

Others are reading

Definitions of ribald from WordNet
ribald (n.)
a ribald person; someone who uses vulgar and offensive language;
ribald (adj.)
humorously vulgar;
ribald language
Synonyms: bawdy / off-color