A phrase used after spending your whole summer out in the sun. In most cases, to show off your hot body near the pool and flex nuts. Being summer burnt is most common in teens or college students because who has the fucking time to sit at the pool all summer? People who are Summer burnt are often maliciously tan from being in the sun 24/7 and are typically easy to spot.
Example 1: Tyrone: The summer burnout is real! I spent my whole summer hitting on hot chicks at the beach.
Jake: Sounds like a fucking golden age m8!