My youngest son is 7 ,my eldest is 12 and has a friend that DS7 loves to copy !
All the facial expressions ,ALL the body shapes EVERYTHING !
Unfortunately this 12 year old walks around with a hunched back (affectation ) (they all do it at school here for some reason 
and a sticky out neck shape ,making him look like a letter L !!
It also comes with a pointy finger shape that comes out of the side of his ear when he is asking a question .
This kid only has to visit for 5 mins and DS7 has lapped it all up .
On my sons friend I don't mind ,and I like the boy :)
On my son ...I really hate it.
I suspect I am being unreasonable ...but it really annoys me ...I want my kid to behave like himself :)
So ...time for blinkers ? or what ?