The word quodlibet is Latin for “what pleases” or “what you will.” A musical quodlibet is a free form, usually humorous piece combining several disparate melodies and/or texts.
The Bach family was a family of musicians and, during family gatherings, they often sang together. Their gatherings usually began on a serious note, and then quickly gravitated to the singing of popular songs, followed by nonsensical quodlibets, which they made up on the spot.
Bach’s Wedding Quodlibet (BWV 524) was probably composed as a gift for a wedding, most likely one within the Bach family. The text is amusing (including a reference to a young pig, among other puns) and deliberate mixing up of parts.
Enjoy a recording of it here, featuring Musica Antiqua Köln, directed by Reinhard Goebel.