How to obtain the last skins/mascots on Crossy Road?

Solution 1:

Hipster Whale - To obtain him, the player must look for him swimming in a river, and jump on him.

Gifty - (must use the character Festive Chicken), Large patches of grass/snow appear rarely, and if one is seen a Christmas Tree will be in the middle. Run into the tree, and get a present.

Found in Crossy Road Wiki:

There are two special easter egg mascots: Gifty and Hipster Whale. Both of the mascots' pictures cannot be seen in the mascot list, (they are blacked out) and the names appear as ????. Neither of the mascots are obtainable in the prize box. Hipster Whale is an easter egg of the games developer "Hipster Whale". To obtain him, the player must look for him swimming in a river, and jump on him. It is completely random for him to spawn, but is most likely with the mascot "Unlikely Cat". To obtain Gifty, you must use the character Festive Chicken. Large patches of grass/snow appear rarely, and if one is seen **a Christmas Tree will be in the middle. Run into the tree, and get a present, when the player dies, it will appear that they got Gifty.