Croc is a skin released during the Happy Weekend offer. It could be purchased with money in October 2016.
Croc could be purchased in one of the following packages:
$9.99 for Croc and 16000 coins
$19.99 for Croc, 3X Mass Boost and 50000 coins
Details of this skin may vary depending on location, platform or time.
Image of Croc skin (new)
An image of the Croc skin (old)