"The picture is vivid in my mind, actually, from that moment," Roberts joked.
"I think I just hadn't really calculated my sleeve length and the waving and how those two things would go together and reveal personal things about me.
"So it wasn't so much a statement as it's just part of the statement I make as a human on the planet."
"Which is very dope, and I'm here for it!" Philipps replied.
Later in the interview, Roberts left the TV host in stitches when she admitted that despite only signing up for Instagram in June this year, she'd actually been lurking on her favourite celebrities' pages for quite some time.
"I didn't feel creepy about it until now … I felt super good about it until this moment," she quipped.
"I was just like, 'What's Oprah up to? What's Busy doing?'"
Roberts, who currently stars in Amazon thriller Homecoming, also explained why she sensationally clapped back at an Instagram troll mere weeks after joining the social media site.
"I didn't mean to clap back, I'd never heard the words 'clap back', something just stumbled into my eyeball range, and I was just being funny — like a schoolteacher," she admitted.
"Then people were like, 'Oh, clap back!' and I was like, I don't even know …?"
