In the Generation I Pokémon games, the "get stuck in a wall" glitch allows the player to become stuck in Prof. Oak's laboratory wall.
Procedure
1. Start a New Game, but do not go into the tall grass yet. Go to the girl that is walking around the town, and block her path until she is forced to go into the grass.
2. Now go into the grass patch next to her.
3. The game will erroneously guide the player into a wall.
Gallery
The player walking through a sign.
The player walking through the laboratory itself.
The player colliding with Professor Oak, but walking through him.
The player moving away from the door.
The player becoming trapped, after walking through a wall.