Sat on my "to do" list for some time has been the task of producing a simple guide to health-checking bunnies. In the meantime, I have lots of strange images of Caroline poking and prodding various bunnies that I need to decipher so I can add instructional text. There's even one in this set of her apparently giving Bacardi a big fat kiss on the lips - not exactly sure how that one fits in as part of the health check guide, but it would seem a shame not include it!
The meaning of these two pics is clear - rabbits seem curiously prone to abscesses and this shows how you can feel for them in the jaw. Early detection of abscesses often means you can avoid any serious problems, so it's definitely something worth doing regularly between their regular vet visits.
As shown, the idea is to feel along the underside of the jaw for lumps. I would also suggest checking the bones from the side too by placing the index fingers along the line of the jaw from ear to nose (like you are underlining both their eyes simultaneously with your fingers).
Simple huh? And don't worry, the disapproving look fades eventually...