Ex-UFC star Tim Kennedy said the reason he decided to get waterboarded was to show the world, "We're not a bunch of spineless cowards" ... and insists it didn't even hurt.
Kennedy -- a U.S. Army Special Forces veteran -- let his friends waterboard him for about 45 minutes over the weekend ... and live streamed it to show the world why it shouldn't be considered torture.
"It feels like you're drowning. It feels like it, but you're not," Kennedy tells TMZ Sports.
"Because the water is going down in the back of your eyes, up your nose, it's pooling in the back of your throat.