Now I DO feel silly! I suppose that's an involuntary reaction to the slight on my masculinity...

I'm not someone who is prone to fainting though, honest. It's only ever happened twice, both times having a few vials of blood taken. My eating habits are shocking though - I think I had just had a bacon sandwich all day, and this test was late afternoon. Maybe that was it.
It was funny really, because the technician said to me afterward - "You should have told me if you were going to pass out!" - as if I had been really naughty. Next time I get the urge to become unconscious, I'll make sure everyone around me knows I'm going down before I hit the floor...