Ever notice

Yesterday during a conversation here at work I noticed something. There were 3 of us having a conversation and I don't know who did it first but somebody rubbed their nose. Nothing out of the ordinary but then within seconds the other 2 are now rubbing their noses. It's like a yawn I think, if someone is talking to you and rubs their nose you rub yours it's just bound to happen. Not rubbing your nose is like trying to stop a sneeze you just can't do it. I know I found myself rubbing my nose with that whole is there a cliffhanger there, is there something on my nose, why are you rubbing your nose. Just one of those crazy things that I notice every once in a while.

What things do you notice that you in return do the same thing then it becomes a big game?