Doctor: He’s just frightened, that’s all.
Liz: So was I! What’s made him like this?
Doctor: Some kind of fear.
That’s not unintentional humor. That’s Three deliberately being a jerk. ^_^
(Once Jo comes into the picture, he’ll do this to her all the time. About half the time, she gets it. The rest of the time, she looks marvelously confused.)