Questioning Her Mental Capacity

One of my students is now at university, and was telling me about another girl in one of her lectures. 

Girl: ... And she, just, like, constructed a fort from tables and chairs.  For no apparent reason.
Me: Why?
Girl: No idea.
Me: ... Does she do architecture? [no] Engineering? [no] So... why?
Girl: I have no idea.  But, we think she might have some... mental problems... I mean, she likes One Direction and Justin Bieber so I do question her mental capactity.

Gold.