Pax: Excuse me, do you have any insecticide spray?
CC(me): Can I ask what for madam?
Pax: There are lots of tiny flies flying around in front of me.
CC(slightly confused): I don't see any flies madam, I think what you can see is dust. Anybody, no? Dust.
Pax: Oh, I guess it could be.
I don't think she quite got the Little Britain reference, but some pax really do leave their brains on the ground.