What is "plonking"

Usage examples of "plonking".

He said it in the slow, plonking tones of someone who is afraid that he might have come up with an important piece of evidence.

The nobles, however, would probably be relieving themselves in thundermugs in their relatively warm quarters, rather than having to unbutton their noble flies - or worse, plonking their naked, shivering, noble buttocks down on a garderobe's frozen seat, and finding that they had stuck to it, more likely than not.