The former Philadelphia Eagles center said on this week's pod he believes the championship bling made its disappearance at some point during a chili tub scavenger hunt that he and his little brother, Travis, were overseeing.

Jason says as part of the game, contestants had to sift through the slop in some inflatable pools for a sock that had his actual SB LII jewelry inside of it.

But, none of the contestants were able to come up with it ... and after searching for it for hours, his pals couldn't find it either.

"I legitimately lost my Super Bowl ring in this event," Kelce said. "They could not find it."

Jason -- who explained the game was actually set up to make fun of his propensity for losing the ring and then finding it days later -- said he's pretty sure that because everything was thrown in the trash following the big event, the prized item is now in a landfill somewhere in the Cincinnati area.

Travis -- who has three Super Bowl rings of his own -- roasted his big brother for involving his jewelry in the game ... calling him "a f***ing imbecile."