go into a song and dance

go into a song and dance (about something)

 and go into the same old song and dance about something
Fig. to start repeating excuses or stories about something. Please don't go into your song and dance about how you always tried to do what was right. John went into his song and dance about how he won the war all by himself. He always goes into the same old song and dance every time he makes a mistake.
See also: and, dance, song