Here's a list of seven real-world items you should never keep in your apartment, the blood of your victims obviously goes without saying.
Just say "no" to keeping illegal substances in your apartment. You risk breaking the terms of your lease and getting kicked out. Moreover, even if the stash belongs to a roommate you can be held accountable. Save yourself fines, potential jail time, and a smeared background check. The latter can make it more difficult to find a decent apartment in the future.
Exotic or Illegal Pets
Sure, that leopard cub looked cute, but now it's a full-grown beast. An illegal pet can endanger you and other people in the building. You also risk serious fines and animal cruelty charges. Don't think about dumping the animal "back into the wild". A somewhat domesticated wild animal won't be able to survive. Instead, anonymously contact your local zoo or other animal rescue organization and investigate your options. It's the right thing to do.
Unless you're building pipe bombs or tinkering with science experiments, chances are good you don't intentionally store combustible chemicals. However: don't mistake the flammable nature of common household cleaners, solvents, and other items. Reduce the amount of chemicals in your apartment overall and make sure to safely store flammable chemicals in the conditions listed on the container.
Heirlooms and Rare Collectibles
Do you live in an apartment with numerous security features and do you personally carry heavy insurance coverage? If not, think twice about keeping valuables in your apartment. Depending on size you can rent security deposit boxes at your bank or more secure location. Your landlord's insurance will not cover your collectibles.
It's estimated that a majority of identity theft stems from people you know or live with; therefore, guard your personal information carefully. A shredder is an inexpensive way to keep your social security number safe. Store other important, original documents in a bank deposit box.
Gifts/Photos from an Ex
Gifts and photos from your former squeeze just make for bad energy. 'Nuff said.
Risque Self Portraits
An actress I knew proudly kept racy naked photos of herself in her apartment. She thought this was ballsy and cool until one day her apartment was vandalized. Now, she fears what ever became of those naughty pictures. One word: Yikes!