YouTube star Harry Brewis, known online as Hbomberguy, started a 57-hour video game stream of “Donkey Kong 64” to aid transgender youth and was surprised by guest appearances from congresswoman Alexandria Ocasio-Cortez and transgender rights activist Chelsea Manning.

Brewis announced in a video that he would be raising money for U.K.-based nonprofit Mermaids, which provides resources to transgender youth.

“I chose to support this charity because as a person living in Britain, I find the media discussion surrounding this issue in my country, especially in its tabloids, to be woefully misinformed,” Brewis said. “I’d like to do my bit to help support the people who do the hard work of contributing to people’s thinking on an important issue.”

He also explains that he chose the charity out of “spite” because comedy writer Graham Linehan, known for his work on “Black Books” and “The It Crowd,” wanted people to protest the organization from receiving funding from the U.K.’s National Lottery.

“So well done, Graham,” Brewis says in the video.“You have a massive audience and the power to choose to fight for progress in all the many forms we need in the world right now and you used it to make sure some children won’t have access to helpful resources.”

Brewis decided to raise money for Mermaids himself and chose the 1999 Donkey Kong video game because he had never finished it as a child.

GameRevolution reports that Manning and “Doom” creator John Romero popped into the Twitch stream. Ocasio-Cortez also called into the stream.

“Thank you so, so much for calling in,” Brewis tells Ocaso-Cortez. “How’s it going over there? The government is shut down?”

Ocaso-Cortez replies that that the U.S. is experiencing the “longest government shutdown in history.”

“It’s kind of a mess right now, and we’re doing everything that we can,” she explains.

“Keep fighting. I think what you’re doing is phenomenal,” Brewis replies.

dude, @AOC called into a Twitch stream tonight pic.twitter.com/KNxSWt2kzB

— Alex Thomas (@AlexThomasDC) January 20, 2019

Cher and author Neil Gaiman also tweeted to promote the Twitch stream.

Who knew when we woke up this morning that we’d be tweeted by Cher and have Congresswoman Alexandria Ocasio-Cortez drop in on the livestream @Hbomberguy started to raise money for Mermaids – currently topping $275,000!#LoveWins ?https://t.co/shT1rY0FiM

— Mermaids ??‍♀️ (@Mermaids_Gender) January 21, 2019

By the end of the stream, Brewis had completed the game and raised more than $340,000 for Mermaids.

Apparently today is #BlueMonday, the saddest day of the year?

This weekend one guy raised over $340,000 for Mermaids by playing Donkey Kong online and uniting the world behind trans kids and the trans community.

Thanks to @Hbomberguy, this Monday is awesome!!#MermaidsMonday pic.twitter.com/Qf8mq2qZU1

— Mermaids ??‍♀️ (@Mermaids_Gender) January 21, 2019