NFL Brothers -- Carnival Kicked Our Asses!

He's 6'2" and 300 lbs ... but Atlanta Falcons defensive end Jonathan Babineaux got straight up WORKED at Carnival in Trinidad & Tobago ... telling TMZ Sports he partied so hard, "By the end, I couldn't hang anymore."

Babineaux and his brother Jordan (an NFL safety) just got back from a week-long rager in the Caribbean -- where they threw on body paint and costumes in the hopes of taking in all that Carnival had to offer.

Instead, Jonathan says he and Jordan got a serious reality check -- "I thought we partied hard. We don't. Those people can party. And it goes on a whole week. I was ready to go after a couple days."

Here's a sample of the party scene, according to Jonathan -- "There's a breakfast party in the morning until about 2. Then the day party until 10. Then the night party until 2am. Then the late late party until the morning. It's non-stop."

Jonathan says he and Jordan tried their best to keep up, pounding rum and pineapples like they meant business -- but by the end, they were completely drained.