A fucking badass; in reference to an ancient elite warrior that were heralded to be the sons of hercules himself. These spartans were raised to fight and were possibly the greatest warriors of all time.
Most know Spartans from the battle of Thermopylae, where a group of approximately 300 Spartan held off thousands of Persians for days. For the full effect of this badassery, watch the movie 300
To be called a Spartan is of the highest honor... 1337ness... gangstaness etc.
Kid: Yo Chels
Kid: You're a Spartan
Chelsea: aww you're so sweet