I took a surfing lesson last summer with my girlfriend and one of her friends. My girlfriend was a little reluctant to get into the ocean for fear of sharks and crabs. While we all understand that shark attacks are rarely fatal, that knowledge brings little comfort when you're hanging your limbs off a surfboard in murky water. The surf instructor tried to allay my girlfriend's fears about crabs by saying, "Sure, sometimes you'll feel them run over the tops of your feet when you're standing, but it doesn't hurt. It just feels like big spiders running over you." I gave him some friendly advice after that. If you're trying to convince people not to be scared of crabs, don't compare them to monstrous spiders. In fact, you can drop the part about them running over the tops of your feet as well.