The Dead Snake was an already deceased snake that was used by Michael to scare his dad while he was asleep.
Plot
Michael brings the snake into the house first scaring Tina with it in the kitchen, prompting her to tell him to get it out of the house. He then goes into Angry Grandpas bedroom and places it in his bed while he's sleeping, telling his dad to wake up and that there's a snake in his bed. A scared Angry Grandpa sees the snake and jumps out of his bed and runs into the bathroom angrily telling Michael to get it out, even after he told him it was already dead.