Where else on the web might identity be more important than say, Facebook?

To be honest, I lie more towards the hiding and lurking side of things on the web when it comes to Internet presence, so asking me to change my profile picture or general visual, virtual representation of myself anywhere other than Facebook would result in an underwhelming amount of attention and remark.

Facebook is more closely linked to the offline social sphere in that it is generally considered an online extension to the offline social world rather than a recreation of it for fictional purposes - there’s usually a much stronger link between our real life persona and our Facebook ones. Hence identity on Facebook is especially important (as opposed to say, a message board or some roleplaying site, or even a personal blog), and impersonation/fake accounts are dealt with zealously by Facebook. What would happen if one were to purposefully alter their exhibited identity, or portray a different persona, especially one that is significantly different from the one people around us are used to? And what about modelling it after another person in a particular social group? Sarah Bien and I are interested in observing the effects of copying each other's style on Facebook with new profile pictures, maybe also with a new cover photo depending.

Here are some possible responses I can imagine receiving:

Chuckling and much amusement by our common friends

Mild confusion, possibly leading to needling questions 

Mirth at poor execution of identity imitation, thinking this is a prank/joke

Most obvious ways of imitation would be exchanging usual clothing and accessories, adopting each other's mannerism and attempting to portray it in a profile picture, etc. Hopefully we will receive notable response from our social circle considering our rather distinct personalities.