The second they tell me the weight I always say, "oh my god, I need to go on a diet."  I don't since I'm very close to being underweight, but the look on every fat nurse's face is always hilarious.  I have a full foot on most of them and easily weigh 100 pounds less, but saying that seems to trigger them to hell.  They never say anything to me, but I always get a dirty piggy look.