It's his gizzard, that's where lizard people store gravel. Lizard people are ancient and more closely related to modern birds.
Discussion
So he's telling Tucker about how he didn't kill that whistleblower, and the whole time I'm just hearing these witch nails on the world's most ragged chalkboard coming out of his mouth.
See, bird lungs only flow air in one direction, so to mimic mammalian speech, lizard people have to eat a witch (usually one of their own children specifically raised for this purpose) and a chalkboard and squeeze their gizzard muscles to produce a simulacrum of speach. The reason you can barely hear the words is because they also hijack your brain and convey most of the meaning telepathically,