That's what we're calling her from here on out. Forget this whole "Pacific Glow" garbage.
It's quite amazing that Hasbro is so afraid of using the name "Derpy" officially, because they incorrectly assume it has something to do with being mentally disabled, yet they let this one slip through. Up there, around Molly's (the Pinkie Pie clone with the glow stick cutie mark) neck is a pacifier.
Why does that matter?
Because it means she's tripping on ecstasy in this scene.
For those of you who don't know, the rave-drug commonly known as "ecstasy" (or MDMA) has a side-effect of teeth-grinding. In order to overcome this, users commonly suck on pacifiers and teething rings to prevent damage to their jaws.
Here's an ABC news article referencing their widely-known application in the drug world.
So there you have it, Molly is gettin turnt on Molly.
Speaking of adult references in this episode: