I just read an interesting post about proposed new laws in the US prohibiting exposing underpants . This is not a new thing and is part of a debate that has been taking place in many countries since the trend of “hip hop” saggy pants.
The first thing that occurs to me is to wonder what the difference really is between underpants and bathers. It seems to me that bathers are simply underpants that don’t turn transparent when they get wet (and which are made of materials that don’t degrade easily when exposed to sea water, UV light, and chlorinated water from swimming pools. So it seems that unless there is some clear legal difference between bathers and underpants such laws will not be effective. Could an underwear company produce products that are essentially the same as it’s regular products but which say “swimming attire” on the label to allow it’s customers to escape silly laws? In fact why not label all underwear as “swimming attire” just in case?
Would the prudes who object to a glimpse of underwear want police to go checking the labels of underwear to determine if they are permitted to be seen? The fascist trend in first-world countries is already quite bad, I don’t think we want to add underpants inspection to the list of police powers. Also it should be noted that a small portion of the police officers are corrupt, the idea of corrupt cops inspecting underpants is really not appealing…
It would be possible to define any clothes worn under other clothes as “underwear”, but this has problems too. For example when I was younger I used to often wear jeans over my bathers when on the way to/from a beach (often there were no adequate facilities for changing clothes near a beach). If I was to wear jeans over my bathers while walking to a beach could I get booked for showing a small section of my bathers over the top of my jeans – and then legally entirely display my bathers while swimming? Of course there are legal nude beaches in many localities, but blurring the distinction between a regular beach and a nude beach by permitting activity that would be “indecent exposure” on all beaches seems likely to have results that would not make the prudes happy.
The next logical implication of laws against exposing underpants is that they encourage wearing smaller underpants. My experience is that it is impossible to wear boxer-shorts without them being exposed above the top of my jeans. Should I be essentially prohibited from wearing boxer shorts because of the risk that if my shirt is not tucked in then someone might catch a glimpse of my underwear?
Now if “underwear” was defined to be “anything work beneath the outer layer of clothes” then what about the situation of having multiple layers of clothes? For example when an athlete who wears a track-suit over shorts, are those shorts “underwear”? If so do they cease being “underwear” once the track-suit is removed? Is there a race condition  where an athlete can wear shorts on the track, a track-suit on the bench, but they have to remove the track-suit as fast as possible because they are committing indecent exposure while removing the track-suit?
If underwear is defined as being the innermost layer of clothing, then what of the practice of “free-balling” (the practice of a man wearing a track-suit with no underpants) and the Scottish tradition of “nothing is worn under the kilt”? Can a track-suit or kilt be defined as underwear? If so how would it be enforced, would police look up the kilts of all men to ensure that the kilt is not the underwear?
As for “plumber’s crack” the only solution seems to be to compel plumbers to wear overalls. Of course then plumbers would increase their rates to cover the expense and inconvenience involved in a forced change of attire. I think that most people would prefer to hire a cheap plumber who shows some “crack” than an expensive plumber.