I'm not sure if he actually uses his tongue to make it like people do, but my mbc makes the tongue clicking sound all the time. We click at each other back and forth when playing, when he's settling down in his cage to sleep, or if he's hiding somewhere like under a blanket and can't see me. He also does a variation of it as a sort of kissy sound when he gives me a "kiss."
And it's definitely very different from beak grinding (he also does that, but not usually in the same contexts; except when settling down to sleep, when he might do either).