Crossy Road has an ever growing collection of different unknown hidden mystery characters that you can unlock. The gacha is where you get every character except for these seven and the Piggy Bank, and the secret characters are the only ones whose identity is unknown until you actually unlock them. *SPOILER ALERT* Read on for tips on how to get ALL of the mystery characters in Crossy Road!
The first mystery character is Hipster Whale, the same Hipster Whale that is the mascot of the game’s developer itself. This one doesn’t show up all that often, but he will often appear in a stream going in the same direction as the logs. When you see the Hipster Whale, jump on it, then jump off of it.
Once you do that, you can either end the stage right there, or keep playing for as long as you want to. When you finish the stage, the Hipster Whale will unlock and will be available in the character select screen; he will also be added to the random rotation. No easter eggs exist with the Hipster Whale, just the fact that you get to use him in the first place.
The second hidden character is Gifty, a Christmas present with feet who jumps around. Getting Gifty requires you to have already unlocked the Festive Chicken, who is free during the Christmas season. If you have not done so yet already, go to the character select screen and “purchase” the festive chicken for free.
Once you unlock it, then go to the character select screen and pick the Festive Chicken, and play. The ground will be all snowy like when you use the Penguin. Eventually you will come across a big, square clearing with a Christmas tree in it. It will look like a normal pine tree except a star coming off of it, and it flashes, and it plays music too.
Go up to the tree and jump to it, getting right next to it (and while you are at it, collect all of the coins that pop up around it, too). Then when you finish the stage, just like with the Hipster Whale, you will end up getting Gifty, the second secret mystery character. Just like with Hipster Whale, Gifty surprisingly has no associated easter eggs.