Someday I'm going to meet someone that none of my friends at the time will have any way of meeting (at a coffee shop, concert, etc), and I'm going to be a totally different person around them. Like, really different. I'll have different mannerisms, different speech patterns, and different reactions to everything (this has to be with a type of person that I actually don't like). When I see them, it will always be one-on-one, and usually in private places to avoid me running into my real friends. They'll grow to trust me and love me as a person that I really am nothing like.
Then, I'll introduce them to my friends and act like my normal self. They'll freak out during this because I completely shifted personalities, and my friends will think they are fucking nuts, because I haven't changed a bit. They’ll think they are crazy, or think I'm crazy. The second is more likely.
Either way, it'll be entertaining.