山洞

山 = 丨 + 凵 : Mnemonic symbol: 山 looks like the tip of a fork. Sherlock Holmes (sh) is climbing a mountain (山) in front of the anthill (an1). He uses a dinosaur bone (〡) as walking stick, and to have better grip he attached a fork (山) to its tip. Unfortunately he accidentally sticks the fork into a receptacle (凵) on the ground of the mountain and gets shocked.

洞 = 同 + 氵 : Doggy Dog (du) finds two twins (同) have fallen down the cave (洞) in the engine's bathroom ((e)ng4). He immediately begins to dig a tunnel to bring them a bottle of water (氵) until more help arrives.