A live taping of the Disney Channel show "Good Luck Charlie" turned into a virtual S&M display ... with a female audience member getting SPANKED over and over again in front of her 2 children ... this according to a new lawsuit.

The woman behind the suit is Kellie Rodriguez ... who claims she took her kids, her sister-in-law and 3 nieces to a taping in L.A. on December 22, 2011 ... when she noticed she was being checked out by the comedian in charge of entertaining the audience, Ron Pearson.


According to the suit, Kellie was later chosen to participate in an audience competition -- in which the contestants would perform a "silly dance" to the Village People's YMCA ... and the winner would get a prize.

Kellie claims she began to dance ... when "all of a sudden and without warning, Pearson started spanking [her] buttocks with his hands."

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