Because I'm a great big swot and have read plenty of academic articles I now know plenty about teaching practices (though, alas, not how to apply them).

One such practice would be creating a 'conjecturing atmosphere' to do this you must not use controlling questions, because this leads to pupils answering mathematical questions by trying to second guess the response you're after rather than considering the answer they'd like to give. Examples of controlling questions would be:
'Is that hwo we talk to each other in thsi classroom?'
'Is that appropriate language for school?'
'Is pretending to have tourettes acceptable?'
'Is jumping up and down on the table going to do it any good?'
etc...

So when my housemate showed me a picture of one of her friends and said 'do you think she's pretty?' I floundered as I tried to think of the right answer and my mind drifted...

How could this situation have been better set up?

Would I be better able to answer if women didn't always respond so curtly if you get it wrong?

Is she pretty anyway?

Would anyone notice if I just got up and left?

In the end I did what most of my pupils so in such situations. I shrugged my shoulders and mumbled a "dunno, yeah, whatever."