I was always impressed by the simultaneous intelligence and stupidity* our dog shows.
Take this for example.
I have just been out to the pet shop for the next door neighbour's cat's present (don't ask, my mother forgot to buy 'Thomas' something, so I got sent). While I was there I realised I'd missed our dog out, so picked him up a furry toy thing that makes noise (will probably only last about 30 minutes on christmas morning before it gets eaten).
When I came home I ran the bag straight upstairs where the dog is banned from, yet when I came downstairs he charged at me, sniffing, barking and licking. It's like he knows....
* eating 'popping' candy and then coming back for more, even though it made you sneeze. Or the classic 'being afraid of your new metal bowl' because you can see your face in the bottom of it when you try to eat.