Charlie: Maybe we could tie some knives to our fingers and we get a little serious about this whole murder thing.
This is an allusion to Freddy Krueger, the villain with the metal clawed leather glove of The Nightmare on Elm Street series who murdered his victims in their dreams.
Attempting to haunt Dennis and Frank, Mac sets up items in the bar similar to the film Poltergeist (1982) and makes a reference to the lead actor Craig T. Nelson.