I think the show is poking fun at all sorts of stereotypes, by
accentuating them, and laughing at them! I think most people
understand that it is funny *not* because of Tim making fun of
Jill, but of the absurdity of him saying these things. But
perhaps, that's just me :-) *I try to never underestimate other
people's intelligences - one might be surprised to see people
smarter than one thinks - they just didn't want to show it off
:-) [construction workers and others thought to be "duuh" class
included]