Let me ask you this, Does he get embarrassed easily?
Not that I have noticed. He more or less does what he wants, but if someone comments negatively about something he does, he gets upset. Example - recently another boy told him he throws like a girl. He was upset, and we discussed it. Issue over.
I think sometimes he is acting like the characters in his video games, he will sometimes flap his arms and jump while running which is definitely not appropriate during a soccer game! :-) We have discussed this with him numerous times, and he has mostly stopped that behavior.
I tend to be rather expressive, must be my love of theatre and the acting classes I took,,,so he may come by it naturally, but need to learn to reign it in. I just don't know enough about how 8 year old boys are supposed to behave! It's been over 40 years since I was that age and I have no experience with being a boy! :-)