A butterfly bob is a hairstyle in which you throw your hair in the air like you just don't care... but not too much of it.
Currently being taunted as one of the chic new haircuts of 2024, the butterfly bob is seriously under-defined. This is a common problem with hairstyles, in which the stylist's interpretation is half the fun, but seriously people.
A butterfly bob is, theoretically, a bob that has tousled layers with a wispy, feathery look. It might be described as a windblown bob. But... that's not what people do. In actuality, a butterfly bob is a bob where you do something that isn't perfectly expected. Often this means a windswept look, but it may just mean an unusual use of layers, an odd cowlick out of place, or ridiculously over-permed and teased hair. It is tempting to define it as simply a bob, but messy, but I cannot emphasize enough how much this is not the case (source).
The matter is additionally confused by butterfly locs, a style of cornrow-like braids that are sometimes referred to as butterfly bobs if they are worn shoulder-length.