This means support for support.
Most commonly used between Myspace contest/layout.. ect sites.
You copy a sites "support code", enter it in a bulliten, and write the subject as "add this site!"
Used as a way to gain more friend requests.
Hey, I have 1,000 friends. Wanna do s4s?
Free Daily Email
Emails are sent from firstname.lastname@example.org. We'll never spam you.