On Instagram you may get a comment saying s4s? Meaning Shoutout for shoutout, a shoutout is when you promote a account to your followers.
Instagam

KittyBaeMeow: s4s?
Baebaeboo: Sure, you first.
by RAWRWRRR KITTY December 12, 2014
Get a s4s mug for your brother Callisto.
used by admins on Facebook. Share for Share. you post their name on your page, they post yours. Useful and effective way of getting "likes"
"hey man, want more likes on your page?"
"sure, how?"
"s4s, bro :)"
by Love Yourself July 19, 2012
Get a s4s mug for your friend Sarah.
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?
by Marisahh August 07, 2007
Get a s4s mug for your buddy Beatrix.
Despite what a lot of idiots have to say about what s4s means, it normally comes into play with myspace sites (i.e. layout/contest/html sites).
Most sites have a support code, and when asked to s4s, two sites swap codes and paste into bulletins so their friends can see the code, and hopefully they get added.
It's not just for "myspace nerds" or whatever. Some sites out there have actual meaning.
"S4S?"
"Sure. Code's on the page. Supporting now."
by homoxcore August 12, 2007
Get a s4s mug for your buddy Jovana.
Has two meanings for two different sites.

on Myspace s4s means

Support for Support

Its pretty much advertising someone else but its done through bulletins. normally people do s4s for Layout sites, Bands etc.

on YouTube s4s means
Subscribe for Subscription
You subscribe to someone because they subscribed to you.
Myspace:
Band: "hey we really need more friends can you help us get more?"
Girl: "sure but only s4s"
Band: "ok cool we posted a bulletin telling all our friends to add you, please return the favor"
-1 min. later-
Girl: "awesome I posted a bulletin to all my friends telling them to add you!"

In return both users receive a benefit.

YouTube:
Guy1: "hey everyone s4s"
Guy2: "cool, i subbed you. now subscribe back! :)"
Guy1: "thanks dude and yes i subbed back"

Both Users receive a subscription.
by gooberyo May 06, 2009
Get a s4s mug for your Facebook friend Abdul.
in carpentry it means sanded 4 sides its for finish work ie; trim and furniture
1x4x8 s4s oak boards
by irish polock January 03, 2008
Get a s4s mug for your father Manley.
hey 4chan is such a cesspool

nah, s4s is nice board
by Worf1337 November 15, 2021
Get a s4s mug for your mate Jovana.