It wasn't about Jughead embarrassing her - though she could see how he would think that considering most of the time her words of warning for him was the Wil Wheaton mantra: don't be a dick - so much as it was trying to do a little bit of damage control and minimize the amount of weirdness this situation was going to cause for all three of them. Because it was weird. For all of them. And it was going to be weirdest for Betty, no doubt, walking into an unfamiliar situation in a foreign place full of unknowns and the only familiar thing there was... complicated. That was the only way Audrey could think of it. Complicated.
She groaned and flopped back, her head landing on Jughead's leg, and scrubbed a hand across her face again. "We're stuck in an unethical human experiment with no clear objective and we're probably being trained for some kind of civilization-ending disaster?" she offered, knowing full well he was speaking on the micro scale, not the macro scale, but choosing to ignore that fact for a moment.
"Uh," Audrey squeezed her eyes shut and sighed, "Betty Cooper just showed up and she's on her way here right now. And we have to tell her about this," she gestured vaguely between them, "whatever this even is. Because it's the right thing to do. I don't know how the two of you left things off, but if it's anything like how I left things off with my girlfriend, we probably wouldn't be in this situation in the first place. But she wanted to see you and I'm gonna try not to third-wheel it for as long as possible, but better rip that Band-Aid off sooner rather than later." There. Best to just blurt it all out at once.