[He blinks a few times, already confused by the lack of punctuation.]

Uh... Lemme see.

[He spends a few moments muddling over the possibilities before speaking again. Mr. White's not wearing the green coat, and neither can Mr. Green, so...]

Mr. Brown's wearin' a green coat, right? So then... Mr. Green's got a white coat, and Mr. White's got a brown coat?