They lie in bed, do a hugely loud poo, and smile in satisfaction.

They can blow raspberries at an incredibly young age (11w is young for that, right?)

They scream when you (or your friends) say "shoes", but calm down if you change the subject to Top Gear (btw, my friends and I did this experiment - shoes/shopping bad, cars good).

They won't wear their hat and sunglasses until you say they look like a cool biker dude... then they sit happily in the carrier, twisting on your finger to go faster. DS is such a boy already!