My boyfriend didn't recognize the RKO Radio Pictures logo at the end of Rocky Horror, so the on-the-spot explanation I came up with was:
Like, imagine if in 30 years someone made an extremely horny and gay musical parody of superhero movies, and just in case they didn't make it obvious enough, at the climax the horniest, gayest character stands in front of a giant Marvel logo.
He seemed to get the idea.