Create your own social network with a free forum.
If you don't want to have your ass banned then stick to these guidelines:
1) Thou shalt not spam a thread with off topic banter
2) Thou shalt not post any pr0n/warez/mp3/ROMs etc.
3) Thou shalt not post anything abusive/threatening/racist etc.
4) Do not post large images with the [img] tag. Make a thumbnail for it or just post a text link.
5) Do not use large or annoying images in your signature.
6) Thou shalt not share torrents via this forum.
Just be nice and have fun.