Well, Allen might try to pull the hand out forcefully. But this could have unexpected consequences like the door breaking open and releasing a horde of mini - ghosts. Then he'd have to deal with them while still trying to free his hand.
Perhaps Allen will realize that the door is a portal to another dimension. And the tiki ghost hand getting stuck is a sign that he's not supposed to go through yet. So he could start looking for a way to close the portal instead of just freeing the hand, which would lead to a whole different kind of adventure.
Another possibility is that a friendly ghost shows up. This ghost could tell Allen that the only way to free the hand is to make a sacrifice. Allen would then have to decide what he's willing to sacrifice. It could be something as simple as a treasured possession or something more complex like a part of his own power. This would create a great internal conflict for Allen in the fanfiction.
Allen could start panicking and call for help. His neighbors might come over, and they all end up having a big discussion about how to get the Tiki hand out. Some might suggest breaking the door, while others would be more cautious.
One possible plot could be that Allen is a curious character who was exploring an old haunted house. His tiki ghost hand, which has a mind of its own, reaches out to touch an ancient door. As it tries to pass through the door, it gets stuck. Allen then has to figure out a way to free it, perhaps by using some magic spells he learned from a local witch.
Perhaps in the fanfiction, the Tiki hand getting stuck is a sign of some sort of magic at work. Maybe the door is enchanted, and the only way to free the hand is to solve a riddle or perform a specific task. This could lead to an adventure for Allen as he tries to figure out how to free his hand.
Well, perhaps in 'pooh gets stuck crossover fanfiction', Pooh gets stuck while trying to follow a new friend from the crossover world. Say it's a crossover with a sci - fi world and he's following an alien through some sort of energy portal, but then the portal malfunctions and he's left stuck in a weird in - between space.
They could use their ninja skills to try and break out of the box. Naruto might try his Rasengan, while Hinata could use her Gentle Fist to find weak points in the box's structure.
One possibility is that they start arguing at first. Draco, being his usual snarky self, might blame Hermione for getting them into this situation. But as time passes, they could gradually start to understand each other better. They might share some of their deepest fears and secrets, which they would never have done in normal circumstances.
There's a chance that he'll meet some sort of magical creature that has made the cupboard its home. This could be a friendly creature that helps him get out or a more mischievous one that makes his situation even more difficult. He'll have to use his wits and magic skills to deal with it.
She might be too big compared to the size of the doggy door. Maybe she was trying to reach something on the other side in a hurry and didn't realize she wouldn't fit.
Well, one possibility is that Will starts to have visions that Vecna uses to manipulate the other characters. He might show them false images of their worst fears, leading to chaos within the group. For example, he could make Eleven see herself losing her powers and being unable to protect her friends.
Well, he could be magically healed by one of his friends. Maybe Lucy uses her celestial magic to call a spirit with healing powers.