Coconut

Coconuts are mentioned briefly in the ''How to Train Your Dragon Franchise.

Description
Coconuts (Cocos nucifera) are a type of palm tree growing abundantly and cultivated around the globe in tropical areas, typically near the water. They prefer sandy soil, warm temperatures, and at least consistent humid conditions to thrive. They are tolerant of saline conditions, as can be found near the ocean. Coconut trees are widely known for their fruits - not nuts - also called coconuts. Coconut fruit contain a single hard seed, which is the source of various food products.

Function
In the Franchise, School of Dragons mentions using coconut oil to soften the leather used for dragon saddles. There is also a few mentions of using coconut as food in some TV episodes.

In reality, there are a variety of edible parts to a coconut seed. The flower buds are edible as well. Even the roots of the coconut tree have been used to treat diarrhea. The wood, coconut shell, fronds, and roots can all be utilized as building material and for the creation of tools and decorative items. Coconut oil and milk are often used in cosemetics and skin products.

Dragons: Defenders of Berk
During the Eel Pox epidemic on Berk, the twins have contracted the illness with some strange side effects. Eel Pox seemed to have made Ruffnut and Tuffnut "smarter", at least in terms of the viewers' perspective (from the perspective of a Viking in the show, they just seemed nuttier than normal). One of the Twin's ideas was the essentially creating ice cream, with coconut as a flavoring.

"Ruffnut has determined that if you boil yak milk, you can freeze it on a stick and dip it in a variety of tasty flavorings, including coconut."

- Tuffnut in "The Eel Effect"

Other Vikings thought freezing "perfectly good" yak milk was appalling.

Dragons: Race to the Edge, Season 3
In the final episode of Season 3, "Defenders of the Wing, Part 1", the Dragon Riders are caught tresspassing on Caldera Cay by the Defenders of the Wing. Queen Mala thinks that the Riders' dragons are being subjugated. Tuffnut and Ruffnut act as "attornies" to plead the Riders' innocence. It doesn't go well.

"Tuffnut: "For the defense, your Queen-ness. Did we sneak onto your island? Perhaps. Did I eat a coconut?" Ruffnut: "Maybe."

- Twins in "Defenders of the Wing, Part 1"

School of Dragons
In the player Quest, "Saddle Up Vikings", the player is asked to collect various items for Hiccup to construct a dragon saddle. One item is oil to soften the leather. Phlegma gives the player coconut oil that she got from Trader Johann.

"You want to soften leather? I have just the thing! I bought some coconut oil from Trader Johann last summer. That will soften the leather and make it smell great, too!"

- Phlegma in School of Dragons