Castle Season 4 Episode 21

Castle: Oh, you should have seen it. Slaughter got the drop on the one guy, but the other guy tried to make a break for it. I had to take his ass down.
Beckett: You what? Are you kidding me? You're a writer, Castle. Not a cop.
Castle: Hey, I can take care of myself. You just never give me a chance.
Beckett: Yeah, because I'm not trying to get you killed. And what is he doing using our box?
Castle: Well, I invited him to.
Beckett: Castle, that's not your place.
Castle: I didn't think you'd mind. Besides, guys like Slaughter, they just float from precinct to precinct, you know? They're like nomads, wandering the streets of New York City, kicking ass and taking names, which isn't the most original turn of phrase, but the character is so great. It's really gonna help me shake up this next Nikki Heat book.
Beckett: Yeah, sure, if you live long enough to actually write about it.