NAN: Simpson, I should generally be UPSET shouldn't I? I mean, the students STILL dislike us, and I just wasted a good hour getting BAT poopy out of the rug.

SIMPSON: Yes, Mrs. Keohane. You should generally be angry.

NAN: THEN WHY CAN'T I STOP SMILING?!
SIMPSON: I dunno, but it also worries me that your hair hasn't moved in a good 5 DAYS.

Shouldn’t Nan be angry?