In ancient Sparta the Gymnopaedia was a yearly celebration during which naked youths displayed their athletic and martial skills through the medium of dancing. The custom was introduced early in the seventh century BC, concurrently with the introduction of naked athletics, oiling the body for exercise so as to highlight its beauty, and the formalization of pederastic pedagogy.

Herodotus

The quotes in this section are retrieved from the George Campbell Macaulay translations that can be found at the Gutenberg project, see: http://www.gutenberg.org/catalog/world/authrec?fk_authors=828 (Note: in that translation The Histories Book I-IV are in volume 1; Book V-IX are in volume 2)

The Histories, book VI - N° 67

Demaratos became an exile from Sparta to the Medes on account of a reproach which here follows:--After he had been deposed from the kingdom Demaratos was holding a public office to which he had been elected. Now it was the time of the Gymnopaidiai; and as Demaratos was a spectator of them, Leotychides, who had now become king himself instead of Demaratos, sent his attendant and asked Demaratos in mockery and insult what kind of a thing it was to be a
magistrate after having been king; and he, vexed at the question, made answer and said that he himself had now had experience of both, but Leotychides had not; this question however, he said, would be the beginning either of countless evil or countless good fortune for the Lacedemonians. Having thus said, he veiled his head and went forth out of the theatre to his own house (...)

Plutarch

The quotes in this section are retrieved from the Aubrey Stewart and George Long translations that can be found at the Gutenberg project, see: http://www.gutenberg.org/dirs/1/4/0/3/14033/14033-h/14033-h.htm

Plutarch's Lives, Volume I (of 4) - N° XIV

In this section Plutarch describes the laws Lykurgus had imposed on the Lacedaemonians during his reign (the message appears clear: no gay hanky-panky during gymnopaedia, unless you're married of course)...

(...) moreover, he imposed certain penalties on the unmarried men. They were excluded from the festival of the Gymnopaedia, in honour of Athene; and the magistrates ordered them during winter to walk naked round the market-place, and while doing so to sing a song written against themselves, which said that they were rightly served for their disobedience to the laws; and also they were deprived of the respect and observance paid by the young to the elders.

Lucian of Samosata (120-180)

The quotes in this section are retrieved from the Francis George Fowler and Henry Watson Fowler translations that can be found at the Gutenberg project, see:http://www.gutenberg.org/catalog/world/authrec?fk_authors=1997

Works of Lucian of Samosata, Volume 02 - OF PANTOMIME

The Lacedaemonians, who are reputed the bravest of the Greeks, ever since
they learnt from Castor and Pollux the Caryatic (a form of dance which is
taught in the Lacedaemonian town of Caryae), will do nothing without the
accompaniment of the Muses: on the field of battle their feet keep time
to the flute's measured notes, and those notes are the signal for their
onset. Music and rhythm ever led them on to victory. To this day you may
see their young men dividing their attention between dance and drill;
when wrestling and boxing are over, their exercise concludes with the
dance. A flute-player sits in their midst, beating time with his foot,
while they file past and perform their various movements in rhythmic
sequence, the military evolutions being followed by dances, such as
Dionysus and Aphrodite love. Hence the song they sing is an invitation to
Aphrodite and the Loves to join in their dance and revel; while the other
(I should have said that they have two songs) contains instructions to
the dancers: 'Forward, lads: foot it lightly: reel it bravely' (i.e.
dance actively). It is the same with the chain dance, which is performed
by men and girls together, dancing alternately, so as to suggest the
alternating beads of a necklace. A youth leads off the dance: his active
steps are such as will hereafter be of use to him on the field of battle:
a maiden follows, with the modest movements that befit her sex; manly
vigour, maidenly reserve,--these are the beads of the necklace.
Similarly, their Gymnopaedia is but another form of dance.