Nintendo Switch game cards are great - they have massive storage capacity yet they're smaller than their 3DS equivalents.
While their diminutive size is boon for when you want to carry around a lot of games with you, there's one issue - the cards are so small they may find their way into the dribbling mouths of babies and young children who are fond of licking, chewing and generally consuming everything that's not nailed down (parents, you know exactly what I mean).
Thankfully, Nintendo has considered this and has covered every Switch game card with disgusting tasting coating. We found out the hard way; while swapping out a game we foolishly placed one of the cards between our teeth to free up both hands, and recoiled at the quite frankly revolting taste.
Here's the official statement on why Switch games have such a funky taste:
To avoid the possibility of accidental ingestion, keep the game card away from young children. A bittering agent (Denatonium Benzoate) has also been applied to the game card. This bittering agent is non-toxic.
It might sound like a totally stupid idea, but it shows that Nintendo really does think of everything.