song and dance

1. A theatrical performance that combines singing and dancing.
2. Slang.
   1. An excessively elaborate effort to explain or justify.
   2. An elaborate story or explanation intended to deceive or mislead.

An elaborate story or effort to explain and justify something, or to deceive and mislead someone. For example, Do you really believe his song and dance about the alarm not going off, being stopped for speeding, and then the car breaking down? or At every annual meeting the chairman goes through the same song and dance about the company's great future plans. This term originally referred to a vaudeville act featuring song and dance. [Late 1800s]

The noun has 2 meanings:

Meaning #1: theatrical performance combining singing and dancing

Meaning #2: an interesting but highly implausible story; often told as an excuse
  Synonyms: fairytale, fairy tale, fairy story, cock-and-bull story