Every human body is just a reservoir for helpful, disgusting fluids and bad habits. Here's a guide to some common habits and why they're considered bad:

• Rolling Eyes: A nonverbal expression of disdain or common side effect of wearing bifocal contact lenses, an eye roll can cause dizziness and disorientation, unless it's coupled with a sarcastic comment, such as, "Great facial expressions, Alice!" or "I guess we'll never know which Darren can't stop burping."

• Biting Nails: It's true that biting nails keeps them at a safe length for petting a blimp or touching a baby's head, but it also has serious health drawbacks. Nail biters suffer from chronic dehydration from not being able to open cans of soda, as well as loneliness after failing to peel price tags off of friends' birthday gifts.

• Grinding Teeth: Teeth make mouths dangerous to navigate during kissing, which is why hopeless romantics are always trying to grind their teeth down into soft nubs. The downside to grinding teeth is that the resulting shavings are extremely valuable and will make you a target for ivory hunters.

• Chewing with Mouth Open: Though you may think you're doing your table neighbors a kindness by showing them that you're not eating their food, chewing with your mouth open produces a disturbing sound that reminds many people of the time their robot drank quicksand.