"Well, I kind of realised the show was hit when we were invited to sing at the Emmys. And we were gonna pass out peanut butter and jelly sandwiches. And also when we got to go on Jimmy Fallon's show," Matarazzo said in a transcript provided by Netflix.
The 15-year-old actor said he always liked making people laugh and the show, currently in its second season, gave him a chance to do just that.
Talking about his experience of coming back to show for the second season, Matarazzo said it felt like a "big family reunion".
"It was great. To go back into production felt like going back home, kind of. It felt amazing. And, to get to show Sadie (Sink) the ways of the kids. It kind of felt like it was a big family reunion. Seeing everyone.
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The actor described the show as a "masterpiece" and also praised the show runners The Duffer Brothers (Matt and Ross) and Shawn Levy.
"They are geniuses. All three of them. I really do believe that. The Duffers made this masterpiece. And it's amazing working with Shawn," said Matarazzo.
The child actor has started an organisation named CCD Smile, that aims to help people with the condition.
"Especially now that I'm in the show, it gives me a platform to start speaking out on what I believe in. I just started an organisation called CCD Smiles. It is to help people with cleidocranial dysplasia.
"It's, to raise money to help people fix their dental problems. To know that this is helping me raise awareness for that condition, makes me feel very good. And to know that people who wouldn't normally afford this, now get to with this organisation," said Matarazzo.