A
sociological term.
Social currency is the monetary unit we use in everyday friendships and conversations. It's things like jokes, little factoids and bits of data that we pick up, not because we're especially interested in the subject - but because it'll make an interesting conversation piece. Something better than the weather.
After all, when we hear a joke, what are we really doing - listening to it for ourselves, or remembering it to retell to another? It's a bit of both - we enjoy the pleasurable laughing response, but we also like the feeling of making others laugh, because of the endorphins it gives us.
Lots of social currency, and charisma in deploying it is basically what everyday conversation and small talk are about.