Script (guión): Idioms, ‘birthday suit’. If you're wearing your birthday suit, you're naked. Basically this is the suit that you are born in. Me and my wife, when we go on holiday, we like to wear our birthday suits on the beach as there's nothing quite like having the wind blowing between your legs on a summers day. Also swimming naked in the sea is quite pleasant, as long as it's not too cold in the water.