It’s Tickle-Me-Wiggly, the toy everyone wants in the StarKid Black Friday comedy-horror musical. My daughter backed the StarKid Kickstarter and we're both fans of their musicals.
Where you can buy online
You can find the design on t-shirts in most stores, but also on other products depending on the store (e.g. hoodies, mugs, stickers, notebooks, phone cases, greeting cards, cushions, socks etc).