Their tongues are pretty blue. I got an opportunity to feed them a couple of years ago on a night tour and was shocked by the blueness. It fell on the darker shade of the spectrum, so might photograph as blacker than the lizard's tongue above. That said, their tongues are blue enough that people watching them eat on any given day always comment on it.

It always strikes me that SF's giraffes can also stick those tongues out a really long way. While we on the subject of what strange creatures they are: how long are giraffes' tongues?