Lots of people do stuff like this for nefarious purposes. I hacked my brothers myspace page and turned it into the page for an 18 year old porn star from moose jaw saskatchewan. (Good lord the amount of friend requests I recieved) Many of them Canadians saying, "I aint never seen anything that looks like you come out of Moose Jaw."
I found it funny, he came to me to help him get his myspace back, lamenting the "hackers" that took it over. Little did he know the responsible party stood before him.
In 01 my first year at ISU, my dorm mate complained about his prom date that stood him up. In a drunken rage gave me her phone number, via much prodding from myself, he was an angry lad. Well, being the sympathetic chap i am, I utilized this information and posted a personal add on yahoo for her, with a nice sexy photo, looking for a sugar daddy complete with her home phone number (this is before the internet police were out in full force, you know).
Which reminds me, my brother recently got a facebook page, looks like its time for round 2 of fucking his shit up. ( I dont actually hack his shit, its just that his passwords and challenge questions are painfully simple. I generally begin by hijacking his email accounts, which makes getting access to his social networking accounts much easier).