When Robin and Ted announce that they're moving in together, his head falls naturally into his hands because it's happening. All those years of false prophesying and it's finally happening – he's alone. Everyone has paired up. Now he'll be tied up in petty arguments about laundry detergent and Swiffers and have to endure more PDA.

The thing is they didn't even notice. Relationships give people blinders. So when Robin bumps into him sliding in the booth, he makes the table wobble when he finishes draining his tumbler.

It's transference of motion. Potential to kinetic. There's no movement after this anyway.