1) Taken from the name Spartacus, it refers to someone who is really smart.
2) It can also refer to someone who has a really smart or good idea.
3) A genius.
1) I am so smart, I am such a Smartacus.
2) That is such a good idea. That was a very Smartacus thing for you to say.
3) You Smartacus! You are such a genius.