Shawne Merriman is furious his good pal and former teammate Antonio Gates didn't make the cut for the Hall of Fame on Thursday ... and now, he's demanding an explanation from the committee.
Lights Out didn't hold back when TMZ Sports spoke with him about the Chargers legend's HOF snub ... saying point blank, "This is pretty much an embarrassment, man."
"This one needs an explanation," he said. "Because if you watch football, in the last two decades, there's no way in the world that Antonio Gates is not a first-ballot Hall of Famer.