We saw an ambulance today go by with lights et al. Sam asked what it was so I was trying to tell her it was for people with boo-boos. Then she started whining and tearing up, whilst holding her leg going, "oooh boo boo *sniffle*." I tried to say it was for BIG boo-boos, but no dice.
Luckily she saw a cat and was done with the ambulance. :)