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A 5-year-old boy whose cancer was declared terminal in June helped his parents write his unique obituary before his tragic death earlier this month.

Garret Matthias, of Des Moines, Iowa, was diagnosed with alveolar fusion negative rhabdomyosarcoma, a rare form of cancer, in September. The cancer attacked the young boy’s cranial nerve, inner ear and temporal bone, the Des Moines Register reported.

Garrett died on July 6, but before he passed the superhero-enthusiast with a sharp sense of humor helped his parents plan his final arrangements, including what his obituary would say.

Emilie Matthias, the boy’s mother, told the Des Moines Register that in the months prior to Garrett's passing they attended several funerals of other cancer patients and he was confused as to why funerals were sad.

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"He would say, 'Why are funerals so sad? I'm going to have bouncy houses at mine," Emilie Matthias told the Register.

The mother said she would talk to her son about death following a melancholy movie.

Garrett Matthias FOX13 SLC 2

Garrett Matthias died on Friday, July 6, 2018. (FOX13 SLC)

"I'd say things like, 'When I die, I want to turn into a star,'" she said. "He'd say, 'I want to be burned like in 'Thor,' and then I want to become a gorilla.'"

Matthias said she and her husband decided her son should not have a typical funeral but something different. The couple asked their son what he wanted instead.

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"We really tried to use his words, and the way that he talked," she said. "Garrett was a very unique individual. What I really didn’t want was for his obituary to be ordinary and to have a really sad funeral. We’ve cried oceans of tears for the last nine months."

In the end, Garrett helped his parents write an obituary in which he disclosed what he liked and disliked. He said his favorite colors were “blue and red and black and green” and his favorite superheroes were “Batman and Thor, Iron Man, the Hulk and Cyborg.”

He said he wanted to be a professional boxer when he grew up and that his favorite people were his family. The things he did not like were pants and “dirty stupid cancer.”

The boy said when he died he was “going to be a gorilla and throw poo at Daddy!”

The obituary continued with details of the burial and ceremony as well as a fireworks ceremony.

“Garrett endured nine months of hell before he lost his battle with cancer. During that time he never lost his sense of humor and loved to tease the doctors and nurses. From whoopy cushions and sneaking clothes pins on their clothes to 'hazing' the interns and new staff doctors, he was forever a prankster. Nothing caught people off guard as his response to 'see ya later alligator',” the obituary read.

Garrett concluded the piece with: “See ya later, suckas! – The Great Garrett Underpants.”

The Des Moines Register reported the boy’s daycare was able to get five bouncy houses for his funeral like he wanted. A celebration of life is planned for Saturday. A GoFundMe was set up for the Matthias Family that has raised more than $39,000 as of Friday morning.