Rita Hayworth

Rita Hayworth was an American actress and dancer.

History
When Mr. Burns was imprisoned at Springfield Penitentiary for art theft, his cellmate had a poster of Rita Hayworth on the wall and was using it to conceal a cross.

Non-canon
In one of his stories, Grampa was attempting to flee from the police, but failed and ended up in jail at Maximum Security Prison. He stayed there for many years, until a poster of Rita Hayworth helped him to escape.

Behind the Laughter
The poster of Rita Hayworth being used in a prison to conceal things and to aid in an escape are references to The Shawshank Redemption.