Sadie Sink was stressed out about Stranger Things kiss

New Stranger Things star Sadie Sink stressed herself out about having to share her first kiss onscreen after it was added to the script at late notice.

The 15-year-old joined the cast of the hit sci-fi drama's new second season as Max Mayfield, and in the season finale, an episode titled The Gate, Sadie's character locks lips with Lucas Sinclair, played by Caleb McLaughlin, as they attend the Snow Ball.

Sadie had no idea she would have to share a kiss with Caleb until she arrived onset to shoot the final episode, and she immediately objected to the storyline amendment, which was initially suggested as a joke by co-creator Ross Duffer.

"The kiss was not written in the script," the actress revealed during an episode of Beyond Stranger Things, on which cast and crewmembers discuss key plot points in the series.

"I get there, the first day of (shooting scenes for the) Snow Ball, me and Noah (Schnapp, co-star) are walking in seeing the decorations and stuff," she recalled. "One of you, I think it was you, Ross, you say, 'Oh, Sadie, you ready for the kiss?' I'm like, 'What? No! That's not in the script. That's not happening.'

"So the whole day I was like stressed out, I was like, 'Oh my god, wait, am I gonna have to...?'"

Duffer and his brother, co-creator Matt, decided to officially add the kiss to the script, forcing Sadie to act it out in front of other castmates' "parents and the crew and my mom" on the second day of filming the Snow Ball sequence.

Ross admitted he only moved forward with the romantic moment because of how Sadie had responded to his quip.

"You reacted so strongly to this (suggestion)," he said. "I was just joking and you were so freaked out that I was like, 'Well, I gotta make her do it now.'"

Sadie isn't the only Stranger Things star to experience her first kiss on TV - Eleven actress Millie Bobby Brown previously confessed her onscreen lip lock with Finn Wolfhard, who portrays Mike Wheeler, in season one of the Netflix show was also a nerve-wracking moment to film.

"It was a strange experience. Having 250 people looking at you kissing someone is like, 'Whoa!'," she recently told Variety. "He (Finn) says I wasn't (his first kiss), but I definitely think I was. I think he was just trying to be cool."