Worf snapping Weyoun's neck in DS9.
Later, the next Weyoun being told, "Maybe you should go in and question Worf again." - or words to that effect.
This, followed by the "escape" of Worf and Dax, when Weyoun had to tell the Founder about it, to which Damar said, 'Oh, I'm sure she'll understand. But if she doesn't, I look forward to meeting Weyoun Nine.'