The term bum flap or butt flap refers in one usage to the rear flap in a

union suit A union suit is a type of one-piece long underwear, most often associated with menswear in the late 19th and early 20th centuries. History Created in Utica, New York, United States, it originated as women's wear during the 19th-century United S ...

, In this usage, it is also sometimes termed as ''crap flap'', ''evacuation flap'', or with some other euphemism. In another usage (

train hopping Freighthopping or trainhopping is the act of surreptitiously boarding and riding a freight railroad car, which is usually illegal. Origins and history In the United States, freighthopping became a common means of transportation following the ...

), the term refers to a piece of removable material that hangs from the waist to cover a person's buttocks. The external flap is of ambiguous origin, but probably was originally intended to reduce abrasive wear to pants. Sitting or sliding on a rough surface can rapidly wear the seat of pants, and flaps act as replaceable buffer material. They also provide some protection from damp or cold surfaces. The freely swinging flap dries faster than wet pants, and can be easier to clean. Bum flaps are often worn as a superfluous

fashion statement Fashion is a form of self-expression and autonomy at a particular period and place and in a specific context, of clothing, footwear, lifestyle, accessories, makeup, hairstyle, and body posture. The term implies a look defined by the fashion ind ...

, usually emblazoned with

punk Punk or punks may refer to: Genres, subculture, and related aspects * Punk rock, a music genre originating in the 1970s associated with various subgenres * Punk subculture, a subculture associated with punk rock, or aspects of the subculture s ...

iconography. Flaps are usually constructed by hand with the most suitable material available, often

canvas Canvas is an extremely durable plain-woven fabric used for making sails, tents, marquees, backpacks, shelters, as a support for oil painting and for other items for which sturdiness is required, as well as in such fashion objects as handbags ...

denim Denim is a sturdy cotton warp-faced textile in which the weft passes under two or more warp threads. This twill weaving produces a diagonal ribbing that distinguishes it from cotton duck. While a denim predecessor known as dungaree has been pr ...

from discarded clothing. Water resistant and thermally insulating flaps are desirable for long distance

freighthopping Freighthopping or trainhopping is the act of surreptitiously boarding and riding a freight railroad car, which is usually illegal. Origins and history In the United States, freighthopping became a common means of transportation following the A ...

rail travel and camping. Flaps may be stitched to clothing, or suspended from the belt.

References

{{reflist Punk fashion 2000s fashion Fashion accessories