Few things are undebatable when it comes to discussing hip-hop, but one of the genre’s absolute certainties is that Kendrick Lamar is one of the greatest rappers working today. This still-young millennium has featured plenty of rappers who couldn’t quite meet the commercial and critical hype. But like a teenage LeBron James, Kendrick Lamar is the first MC of his age cohort who actually exceeded the expectations that had been building since his breakthrough, 2010’s Overly Dedicated. His major label debut good kid, m.A.A.d city considered a classic, and his multiple RIAA plaques, Grammy wins, top slots on album of the year lists, Pulitzer Prize since then demonstrate that he’s yet to fall off.

Kendrick Lamar is perhaps most significant because he’s one of the few rappers who’s consistently shown that commercial success and traditional lyrical ability don’t have to be mutually exclusive. The biggest example of that ability is his most recent album Damn, which combined stadium-filling mainstream ambition with intense introspection and some evergreen catchphrases (“What happens on Earth stays on Earth!” is tattoo-able). Lamar’s current mainstream dominance has been built upon over a decade of hard work: He’s been releasing mixtapes since he was 16 years old, years before he became the potential top-five-dead-or-alive he is today.

Kendrick Lamar turned 31 yesterday, and hip-hop heads are continuing to look forward to how he’ll top Damn, the first hip-hop album ever to earn a Pulitzer Prize. But even though he’s given so much of himself in the booth, there are still some facts about him that may surprise even the most astute follower. Here are 15 things you didn't know about Kendrick Lamar, including what he considers to be his worst song and that time he was signed to Def Jam.