Any walking mob that fits in a 1 block footprint can attempt to walk through corners of solid blocks, causing it to hug the corner. This probably affects most any mob with the common wandering AI, though I couldn't find a method of consistently producing the result with larger mobs.

• Place an adequate mob in a 1x1x2 space walled off with solid blocks, including external corners
• Wait an amount of time that provides substantial evidence that the mob will not move
• Remove an external corner of the enclosure so that space is provided for the mob's hitbox at that spot with no change in elevation
• The mob will eventually walk towards the corner, as though expecting to move through it.

If the walls are removed soon after the mob contacts the wall, the mob will move forward, suggesting that it intended to walk through the corner instead of stopping once it hit the wall. Cave spiders will also climb the wall even if they had no intention of doing so with all four external corners present. If multiple entities are put into the same spot in vines (to bypass entity collision), they can all be manipulated to stand in the exact same coordinates using this method.