Well-- [ And he glances around too, and smiles back at her. ] --they have a habit of doing that.
[ He picks one up, a little gray one that sits in his hand neatly. ]
Earth used to be overrun by rodents, such that people commented on their proclivity to breed, but even back then there was never anything like this. Nevermind that on most planets - including this one, it seems - tribbles lack any predators. They can cause a great deal of damage in no time at all.