Welcome to the Beyond Blue Forum.I think it was a pretty good idea to see what others thought about your activity.
I have to ask - what did your brother think, having his kneecaps talk to each other, like did he join in the game and was happy with things?
I'm sorry your friends and you had a parting, it would have hurt of course and raised emotions in anyone. For some people this results in crying, or being cross, retreating or other things.
I can't say much about the activities you describe, telling jokes out of the blue and laughing hysterically, crawling around, trying to bite your screen and all the rest.
I can understand if you find it worrying and puzzling, and pretty inconvenient too. Also a bit of a worry that it starts without you intending it to. None of this sounds actually harmful (except maybe trying to bite your screen)
Is there someone you can talk to about this and say how you feel? For many mum or some other family member is a good choice, for others a councilor or teacher at school. If you are stuck you can always give the Kids Help Line (1800 55 1800) a ring. If you prefer you can web-chat with them instead on
which is pretty good, though sometimes you have to wait a bit for a councilor to become free, it's very popular. Ringing can be faster.
So please come back and say what you think, you may stop a fair bit of worry if you reach out now.