Is it socially acceptable for individuals to wear clothing typically associated with the opposite gender? What are some reasons for or against this practice?

There are many reasons. This can be broken down into the eight broad categories below, though most people only think of no.6:

d) Stunt doubles.

4) Entertainers.

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In Lancaster County, Pennsylvania or Salt Lake City it won’t be accepted. In Rio or Douarnenez at Mardi Gras it’s practically compulsory. (Seriously, I counted the men in skirts in a bar in Douarnenez: one in six.)

c) Drag queens and Drag kings – an exaggerated satirical sub-section of the light entertainment field.

6) Transvestites – what most people first think of. For transvestites, crossdressing is an end in itself; motives many and various. For most, these go back to childhood or before birth and are obsessive.

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Don’t do it unless you want to.

8) Those forced into crossdressing. This category is included for completeness but barely seems to exist in real life today. It was however observed in the period 1850-1950 when boys were occasionally forced into girls' clothes as a punishment at school or in the home. It is a staple of fiction – to escape from danger (Some Like It Hot), to obtain a job (Tootsie, Mrs Doubtfire), or forced by a sadistic female relative (much transvestite erotic fiction).

2) Fashion crossdressers - some metrosexuals and most women fall into this category. Women in trousers – seen as a sexual and social aberration in 1900 – had become the norm by 2000.

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If you’re going to do it, do it 100% and do it well. You’ll enjoy it all the more and so will the people around you. It’s often good for a round of applause or a free drink.

If it’s merely your sexual fetish — see 3) above — don’t do it in public. You’ll look ridiculous and possible offend decency laws.

7) Transsexuals – for many of them the cross-dressing is merely an incidental stage in their transition of identity. Once achieved, the wearing of the clothes of the other sex becomes the norm, and can no longer be called crossdressing.

What are the most outrageous violations of restaurant buffet etiquette have you seen?

a) In serious entertainment, actors playing a role. From Mark Rylance as Cleopatra or Judi Dench as Olivia to Antony Perkins in Psycho. Japanese Kabuki and Nō players. Sopranos singing "breeches" roles in opera.

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Socially acceptable? It depends on which bit of society you live in.

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Don’t do it in places where it’s illegal, like Russia.

3) Fetish crossdressers - who use clothes as a substitute for, or an essential precursor to, sex. This is commonest among teenage boys, but usually disappears or develops into transvestism later. It is rarely seen in public, although the word "fetish" is often misapplied by those who should know better.

1) Occasional crossdressers - Hallowe'en, practical jokers, fancy dress parties, students' rags... etc.

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Reasons against it? Basically,

5) Other professionals: the occasional spy/undercover policeman/criminal in disguise. Gay prostitutes.

b) In light entertainment: female impersonators/comedians; pantomime dames in British theatre.

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