The Monster Mash by Bobby (Boris) Pickett and the Crypt Keepers hit number one on the Billboard Hot 100 on October 20, 1962 and has been a perennial Halloween favorite ever since. The Monster Mash dance is similar to another popular dance craze that started about the same time, "the mashed potato." In both dances, you grind one foot into the ground while simultaneously walking in place and swiveling your foot. The only difference is that you add some creepy, ghoulish arm movements while doing the Monster Mash.
Choose a ghoulish stance. For example, have one arm hanging limply at your side with your hand curled under and the other hunched up and rigid.
Lift your right foot off the floor with your knee slightly bent and out to the side. Shift your weight to your left foot.
Stand on the ball of your left foot and pivot on left foot to the left then back to the right.
Put your right foot back down on the floor close to the left foot. Turn your right foot slightly in and up on the ball of this foot.
Lift your left foot off the floor with your knee slightly bent. Shift your weight to your right foot.
Stand on the ball of your right foot and pivot to the right then back to the left.
Put your left foot back down on the floor close to the right foot. Turn your left foot slightly in and up on the ball of this foot.
Continue to pivot and mash your feet into the floor. Try to keep each foot mash with the beat of the song.
Keep practicing the footwork until you can transition from foot to foot smoothly and in time with the music.
Add more arm movements when you're comfortable with your footwork. Keep your arms in the same position the whole time, alternate them every few moves or between each foot transition.