'Bachelor' Host Chris Harrison: Lauren B's 'Engagement' Ring Is a Total Laugher!!

'Bachelor' favorite Lauren B.'s mystery ring is either a Cracker Jack prize or the most embarrassing engagement ring in history ... according to Chris Harrison.

"The Bachelor" host could barely contain his laughter outside Staples Center Tuesday night when we asked about the ring that had fans thinking Lauren was the winner. Chris calls us out for missing the obvious sign Ben didn't put that thing on Lauren's hand.

Watch, he also jabs our photog pretty good for filling out a Bachelor bracket. Which is totally deserved.