A Shiny Nickel is a sexual favor usually given by a girlfriend, wife, or an escort (prostitute). To give one a Shiny Nickel the female must first lather the males' anus with semen and vaginal fluid. Then she must "shine" his anus with her toungue until squeaky clean.
Man #1: How was that date last night?
Man #2: Amazing! After the movie she gave me Shiny Nickel in her Grandma's bedroom!