A band that plays primarily in bars and always sounds better when the audience (and most of the time) the band is drunk. They are usually extremely entertaining and have a lot of novelty songs, written to get a laugh. They are not always that talented, but it doesn't really matter.
Hey! Did you catch the bar band last night?
--They probably won't ever hit it big, but I was laughing my ass off after I drank a few Buds.