Sydney Sweeney Says Dad Walked Out on Nude 'Euphoria' Scenes

Sydney Sweeney's dad apparently couldn't stomach his daughter's explicit scenes in "Euphoria" -- which kinda makes sense ... 'cause she bares it all and then some.

The actress dished to "TODAY" about how her folks took her early work on the hit HBO show ... where she's featured fully nude a number of times, not to mention straight-up sex scenes. As she puts it -- her father, Steven, wasn't up to watch his daughter in that context.

She says, "Yeah, I didn’t prepare my dad at all," going to explain that when her pops and grandad initially watched her in "Euphoria" -- presumably season 1 -- they "turned it off and walked out." Sydney rhetorically asked ... "I mean how do you bring up a conversation?"

It's interesting ... it sounds like Sydney looped her mom in on what she was doing on set, saying Lisa was prepped and knew what was coming -- adding that she'd come to visit her daughter on set regularly. Sydney says with her dad ... they just don't talk about work.

BTW, the way Sydney tells it ... it doesn't sound like her father/grandpa watched her in "Euphoria" ever again after seeing her naked -- but adds, her g-ma is a big fan!

Sydney has talked about her raunchy scenes -- of which she's done several between a few different projects of hers now -- and says she's not afraid to go there as an artist ... arguing that she's willing to do whatever the work requires of her, as long as it serves a purpose.

She has said, though, that pervs and trolls are constantly screengrabbing her nude scenes and tagging her family members -- including young cousins -- and she says that sucks.