For a refresher, we're talking about the scene in episode four where Cassie, played by Sweeney, vomits while drunk in a hot tub with friends. See the clip below.

Sweeney confessed to feeling "really disgusted" by the scene and revealed that the fake vomit was expelled from her mouth through an "invisible tube."

The star told the media: "During the hot tub scene, during the throwing up, I got really grossed out."

She elaborated: "They had this invisible tube that looked like a horse bit and they put it in my mouth and I had to somehow hold it and make it look semi-normal and then throw up over everyone which was… it was so gross."

Sweeney also revealed that director Sam Levinson instructed her character to drink a different type of alcohol in each shot to highlight Cassie's level of intoxication.

"Every shot wanted her to be drinking a different bottle," said Sweeney, adding: "So if you notice, every single shot she has a completely different bottle in her hands. By the end of that episode, I'm like, how many drinks is she in? She was gone."

Despite the fake vomit and tears, Sweeney said she "loved" filming the scene because she and her co-stars were all "together."

"A lot of times we don't get to have many scenes where we have a bunch of girls together and we were literally in one room. So, it was chaotic but fun," the star said.

Sweeney's portrayal of Cassie earned her an Emmy nomination for Best Supporting Actress this year, alongside Patricia Arquette (Severance), Julia Garner (Ozark), Jung Ho-yeon (Squid Game), Christina Ricci (Yellowjackets), Rhea Seehorn (Better Call Saul), J. Smith-Cameron (Succession), and Sarah Snook (Succession).

Sweeney started her acting career at the age of 12 in 2009 with a cameo appearance on NBC's Heroes.

She later portrayed Emily in the horror film Spiders 3D, and also had roles in The Handmaid's Tale and HBO's Sharp Objects.