[ Given the sick beats John knows Dave lays down, and 13 years of observing other people, he can guess the bouncing is probably music-related. After a moment, anyway. He does wonder if there's actual music playing, though. There could be, maybe over a speaker system. He'd certainly be none the wiser.

Despite having more food than Dave to begin with he manages to mostly clear his plate and get through both milk cartons long before his friend. So he's able to just sit and watch Dave eat. Which is surprisingly interesting, actually, what with Dave's weird eating habits.

...Yes, Dave, John is just sitting here staring at you while you eat, what of it? ]