When, after the first session of IQ/achievement testing for your 4 year old at a very well known gifted child clinic, the tester (who also happens to be the director of the clinic) comes up to you and says that she has never seen a child with DS's intuitive math ability before. ...and cue parental amazement/utter terror!

(Granted, this is the same kid that totally sandbagged one of the subtests (I don't know what it's called, but he had to name as many [insert items] as he could...be it types of food or clothes or whatever, and essentially had a melt-down of "I just don't want to do that!" Yeah, that was super fun. Really puts it all into perspective for you, lol.)