otaku_emmy said:
I've never thought of doing that. I've always just removed them and let it go to default. It'd be funny to make it something cute or trolly though.
This is the one I use for that.

otaku_emmy said:
Social media, basically. I read somewhere that it stood for "social media services/sites", but apparently that's not true. "SMS" actually stands for "short message service". But anyway.
SMS and MMS are the texting protocols that cell phones use. If you heard someone using it for something else, they were mistaken.

*Edit: They probably meant SNS which is often used to mean Social Networking Services.