SFS on Instagram means "shoutout for shoutout" or "spam for spam". It is a self-promotion tool used by users to cross-promote each others content and increase exposure and followers. When users agree to an SFS, they tag each other in a post to direct their followers to each others pages. The hashtag #SFS is almost always paired with the post on Instagram. Users may also DM or tag each other in an SFS post to get each others attention. The intention behind SFS is the same on other social media platforms like Snapchat and TikTok.