SpongeBob and Patrick race to Sandy's treedome to hang out with her. However, the dome has a metal cover over it and a "Keep Out" sign on the front door. In the entryway, they find a television, which turns on and plays a video of Sandy dressed for bed and gobbling acorns. The recording of Sandy explains that she is hibernating for the winter and asks for no one (especially SpongeBob) to disturb her. However, Patrick opens the door anyway to reveal the dome's environment completely covered with snow.
SpongeBob and Patrick quickly take delight in the snow, even being able to remove their water helmets because of the snow's moisture. Upon hearing a strange sound from Sandy's treehouse, the two of them go to investigate. They discover Sandy, many times her original size and sleeping soundly. At first, their gentle prodding and poking do nothing to wake her from her dreams of catching the outlaws Dirty Dan and Pinhead Larry. Soon enough, though, their merrymaking takes its toll, and Sandy suddenly rises, assaulting SpongeBob and Patrick in her sleepy stupor. She then falls back into her bed, asleep once more. A pair of earmuffs is fashioned from Patrick's belly button lint and placed over Sandy's ears to prevent Sandy from waking up.
SpongeBob and Patrick leave her room to continue playing in the snow. They pretend to be the outlaws from Sandy's dream but start fighting over which one of them will play the part of Dirty Dan. Their roughhousing knocks Sandy's earmuffs loose, allowing her to hear the ruckus and set upon them and attacks them in further half-asleep fury. Being battered and bruised, and with the winter storm growing more intense, SpongeBob and Patrick try to leave but find that the door is frozen shut, leaving them trapped in the wintery treedome.
Unable to escape or survive in the cold weather, they go into Sandy's room and, throwing caution to the wind, rip off all her fur. With their new fur-lined winter attire, SpongeBob proclaims that they are now ready for the "longest, coldest winter ever!" However, winter immediately comes to an end, and Sandy wakes up with her winter pounds shed. She is surprised to see SpongeBob and Patrick but soon realizes that, with them wearing her fur, she has none left, so she becomes angry at them and Spongebob and Patrick realize that ripping her fur off wasn’t a good idea. To punish SpongeBob and Patrick, Sandy drinks lemonade with them, whose bodies are wrapped around her to provide her new spring coat to keep her warm until her fur grows back.