Backslash
Used in the same manner in speaking as "/" is used when typing in emotions, actions, or reactions in text.

In text, (such as in a chat room online) "/" is understood that it is not to be spoken, but sets the platform for an "action" or emotion one is trying to express.  the reason that this tool is used in text is to express things that can only be expressed in person, and not through text.

When using "backslash" out of text, it has to be spoken, then it is followed by the emotion or "action".  the reason that this is used at all, is to exaggerate a thought, feeling, or show a desire to do something, as it is usually exaggerated in the text form as well.
In text:

Person 1: I just bet my friend 300$ that he wouldn't eat a pile of dog shit... now I'm out 300$ dollars!

Person 2: OMG! /vomit

Person 3: Wtf?  Seriously? /dies


In real life:

Boss: We are having to cut back on workers, and you are going to be the first one to have to go.  I'm sorry, You're fired.

Fired Employee: What?!  Backslash slap! (Does not actually slap him)


Girlfriend: It was nice having sex with you... but I wish your cock was a bit bigger.

Boyfriend: Er.... backslash embarrassed.


Both "Backslash" and "/" can be used in all of the exact same ways.