Muay Thai Cookie is an S-grade cookie released on 18 Dec 2014, the same day with the release of Cookie Run: New World. This cookie was given for free from the promotional newsletter for Thailand and Japan users who registered their email before 14 December 2014 via promotional link provided, however other players still can get the cookie for free by inviting 40 friends with the 5th and 6th Invite Event.
Muay Thai Cookie has the power of destroying obstacles while during the superpower mode (marked with a fire blast behind the cookie) and also has a small chance of destroying obstacles outside the superpower mode. Muay Thai Cookie also revives with some amount of Energy only when his energy runs out, and gives 4,000 points for destroying obstacles during superpower mode, while 1,000 points for destroying obstacles while idle.
Destroys a certain amount of Obstacles when running into them. Once he's pumped he annihilates all Obstacles. When he runs out of Energy he revives through sheer willpower. He also gets extra points for destroying Obstacles (upgrades give him fighting spirit and he revives with more Energy).
Hot peppers were directly added to the dough to make this one spicy Cookie. His desire to be the best is unbeatable. He will use pain as his weapon. All the Cookies say that Muay Thai Cookie stayed in the oven a little too long to become tough. He's now got quite a fan, which goes perfectly with his charisma. He's thinks his hairstyle shows his diligence so he'll never change it.
Muay Thai Cookie gains extra points for destroying obstacles at any moment, whether it is being pumped or not. It also applies to pets, treasures, and jellies that destroy obstacles such as the Jellyco Cube, Jellyco Cube's Lost Jellyco and Giant & Coin jellies
Combine with Random Boost : 70% Invincibility for 100% chance on destroying obstacles upon impact. This is because Muay Thai Cookie has an innate 50% Invincibility to Obstacles and the percentages are additive, not multiplicative. Muscle Cookie can also take advantage of this. However, this is no longer applicable, since Muay Thai cookie does not have the 50% invincibility to obstacles after the Wrath of the Dragon update.
Muay Thai Cookie was the second cookie which can be obtained from Invite Event reward.
Muay Thai Cookie's previous unlock requirement was to get 108,000 Coins. This was then changed at some point during an update, and make it harder by getting 150 friends.
Muay Thai Cookie's name in Korean is Red Pepper Cookie.
Muay Thai is an actual fighting technique that exists in the real world. The Wikipedia entry states this:
Muay Thai is a combat sport of Thailand that uses stand-up striking along with various clinching techniques. This physical and mental discipline which includes combat on shins is known as "the art of eight limbs" because it is characterized by the combined use of fists, elbows, knees, shins, being associated with a good physical preparation that makes a full-contact fighter very efficient.