The evidence
Jen’s description of the green MITH mug would make you think this is just an ordinary coffee cup, but a closer analysis of the photograph reveals that this is, in fact, a Reversed Gravity MITH Mug which rose to the ceiling and then got stuck there: it’s upside-down, and the shadow in the upper-left corner of the mug indicates that the light source is coming from one of windows across the room (i.e. from below the object). If you look closely at the reflection, you’ll see that Jen is looking up at the mug while taking its photo. Jen ordered these special mugs in 2010, when MITH was still in its subterranean McKeldin digs; the garish lime green enamel was intended to act as a cheap substitute for a sunlamp to combat the staff’s lack of sunlight. If you’ve watched Season 5 of the new Dr. Who series, the green MITH mug is basically a precursor to the gravity globe (rises up to the ceiling, is a substitute for natural light). Jen is a huge Dr. Who nerd and player of VVVVVV, but was too embarrassed to give everyone on the staff a sonic screwdriver or indie game; instead, she created an object that would reference the show in an extremely subtle way.
Three cheers for Doctor Who and gravity globes!