Halloween just so happens to coincide with a blue moon this year — an astrological coincidence that hasn’t happened since 1944.Denny’s, the fast-food chain known for its breakfast and nonstop, 24-hour service, is going all out for spooky season — by dying its food blue.That’s how we ended up here, with Denny’s blue-bread sourdough sandwich.Twitter users had plenty of feelings about the sandwich, which, while being totally safe to eat, does look a bit like it’s held together with moldy bread.As Delish reported, the promotion is only available at locations in the Miami area.That’s because the blue dish is an alteration of the chain’s Moons Over My Hammy sandwich, which was originally named after the 1935 song “Moon Over Miami”.So, not everyone will get the chance to eat the ghostly sandwich .To get in the holiday spirit, the chain also changed its Twitter name to “Halloweeny’s” and got some laughs from its followers with a series of horror movie-themed tweets