the play's subtitle is 'what you will' - which reflects the spirit of abandon which prevailed in elizabethan england on january 6 - twelfth night, or the feast of the epiphany.
the rigid social hierarchy gave way to general debauchery and dressing up.
the play's famous opening line -

'if music be the food of love, play on,
Give me excess of it that, surfeiting,
The appetite may sicken and so die.'

- is delivered by a character called orsino, a duke.
there is a record that queen elizabeth's guest on twelfth night 1601, was an italian nobleman called orsino ... he wrote to his wife that he was entertained that night by a comedy, with music and dances', and it is known that shakespeare's own theatre company "lord chamberlains men' performed the play.

i've never seen it performed - have you?