The worst things you can put down a garbage disposal, obviously, are fingers or other body parts (for your own sake, please do not Google this). And you don’t have to be a plumber to recognize the awful, telltale grind signaling that a fork or other stray object snuck in unnoticed. Those mistakes are obvious.

But there are plenty of other, subtler, silverware-free ways to misuse this kitchen appliance and risk a costly clog. “Most people do not use garbage disposals correctly,” says Paul Abrams, director of public relations for the Cincinnati-based Roto-Rooter Plumbing and Water Cleanup. “They were made to handle residual food scraps on plates, which would otherwise build up and clog a drain. They were never meant for cleaning out your refrigerator.”

Kitchen clogs are the second most common reason (after toilet issues) Roto Rooter gets called to a home. “For a lot of people, it tends to be ‘out of sight, out of mind’ once something goes down the disposal,” Abrams says.

But pipes have a lot of twists and turns, from the P-trap, a U-shaped pipe below the disposal, to the branch line that connects your kitchen sink to your home sewer and is only about two inches in diameter in most homes, according to Abrams. “It doesn’t take long for clogs to form, and then you’re paying a plumber a couple hundred dollars to straighten things out.”

Protect your pipes by avoiding these ten clog-causers:

1. Egg Shells

There’s a persistent myth that tossing egg shells or other items down your disposal will help keep the blades sharp. Just one problem, says Abrams: Garbage disposals don’t have blades. Instead, they have small moving parts called impellers that swivel to crush and pulverize food and debris. “Egg shells are somewhat heavy and will sit in a pipe, so if you have a sewer with a low spot in it, what we call a belly, they will gather in there,” he says.

2. Grease

Any kind of frying oil, bacon grease or other fat are a plumber’s number-one enemy. Though they are liquid when you pour them down the drain, they solidify and coat your pipes, causing build up that leads to clogs. These monster buildups, known charmingly as “fatbergs,” can be problems at a larger level, too. Instead of tossing your grease down the sink, invest in a grease can.

3. Pasta and Rice

Who knew that carbs were bad for your disposal? “Starchy foods turn to goo after sitting in water for a while,” says Abrams. “Even if it gets past the disposal, it will clog the kitchen drain eventually.”

4. Peels

Potato peels have a starchy consistency, but Abrams says he frequently gets complaints from plumbers about citrus peels. People put them down the disposal to clean it or help with odors, not knowing the peels won’t get fully chewed up and could cause clogs farther down the pipes. Lemon juice, baking soda or ice are all better options.

5. Seeds

Like shards of a broken glass, seeds are small enough and hard enough to cause problems. “Anything larger than a sesame seed can get between the housing and the moving parts and jam your disposal,” says Abrams.

6. Fibrous Foods

Fiber is good for your gut, but it will do a number on your pipes, Abrams says. Celery, asparagus, corn husks, rhubarb, artichokes—or anything with lots of fibrous threads—is a no-no.

7. Poultry Skin

The day after Thanksgiving is Roto Rooter’s busiest day of the year, and that’s mostly caused by meal prep. “Just about everything associated with a turkey dinner is a potential clogging agent,” says Abrams. Small bits of meat without bones (“It’s amazing how many people put bones down there,” he says) are okay, but chicken or turkey skin is rubbery and won’t grind up small enough, so toss it in the trash instead.

8. Coffee Gounds

Small amounts in a fine enough grind are okay, but regular coffee grounds tend to be dense and heavy and a clog risk. Not to mention stray beans can act like seeds and jam your disposal.

9. Nuts

We can’t really imagine a situation where you’d want to put nuts down your disposal, but doing so en masse will turn it into one big peanut butter jar.

10. Pet Food

Wet or dry, pet food can be an issue. Depending on the formula, it’s got some combo of oily, greasy, gooey or fibrous ingredients that don’t bode well for pipes. On the rare occasion that Fido doesn’t scarf his dinner down, use the trashcan instead.