DOOM: 17 Easter Eggs, Secrets & References You Must Find

15. It's Your Birthda-Oh

Found inside the Titan's Realm level (and the above video will help you in locating it yourself), it seems someone's birthday celebrations went awry, as all that's left is a party hat and balloon.

Shooting the balloon either results in children cheering or booing, but sadly the cake can't be interacted with, nor does it respond to being shot.

So, in a way... the cake is a lie? Portal fans will know what's up, but who knows how intentional it is.