山溝

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.

沟 = 勾 + 氵 : In front of the outhouse (ou1) Guy Fawkes (g) drew (勾) a photo-realistic comic (勾) of an open gully (沟) on the floor. The people are afraid to step onto it because it looks so real. They only start to believe Guy Fawkes that it's not as he spills a bottle of water (氵) over his chalk painting.