When we talk of 'spoilers', we usually mean plot twists - e.g. you're actually your own uncle's uncle's nephew sent back in time to cut your child's finger off. More rarely, and more delightfully, we face odd surprises in what a game does or becomes. What's so great about Frog Fractions? Mate, go play Frog Fractions yourself.
Metal Gear Solid games hold many surprises big and small (I still chuckle at Snake Eater's glowing mushroom chat), and I wouldn't want to ruin any in Metal Gear Solid V: The Phantom Pain [official site] for you, but this post is about a small and charming thing you'll only see on one day of the year so... maybe have a peek below?
The Phantom Pain asks you to input a birth date at the start, then has a surprise for you in-game on that date. If your birthday (real or fake) is coming up, heck, maybe consider waiting. If not, aww, look at this:
Reddit user 'Razorgc' explains: "My birthday just happens to be September 2, and after finishing a mission Ocelot came over the radio and said, "Snake, you have to come back to Mother Base! It's an emergency!" I just assumed it was part of the story. The game immediately takes you there and this happens."
Quiet has a surprise too, if you've recruited her:
I can't imagine I'll post many of these oddities, but this gave me a big old grin on a grey Thursday morning. Not least of all for that non-copyright-infringing birthday song.