The bitter taste of video game cartridges

They're coated in denatonium benzoate (DB), the most bitter chemical known to people.

After incidents of kids swallowing gaming cartridges, in 1995, many states passed legislation to make it mandatory for certain products to use DB. All major video game manufacturers have done this as standard practice. It's not toxic despite the strong bitterness. But it is used in toxic products like antifreeze, which would taste sweet without DB.

How effective it is has been debatable. If you tell people they could taste the most bitter thing on the planet, someone's going to try it.