For ages we have been trying to teach Harri to give us 'the thumb'. Whenever he does something cool we will give him a hi-5 or the thumb. He always tries to give it back to us, but always ended up putting up his pointer finger, instead of his thumb! It was like he was going to shoot us!
Finally last week he got it! I was watching him one day and he kept putting his thumb up and then down again and then up again. He then said to me 'is this right Mum!?' and showed me. I told him it was and he yelled 'cool dude!', as that is often what we would say to him when we would give him the thumb.
Now he is always going around giving us the thumb and yelling 'cool dude!'.