Ooops.
Most UFC fighters would be PUMPED to be on "Kimmel" -- but not UFC fighter Jake Ellenberger ... who got caught in a big time lie during a political bit on the show last night.
Kimmel was doing his "Lie Witness News" segment -- where he was out to bust people lying about voting on Super Tuesday.
The set up -- there was NO presidential voting in California yesterday ... but Jimmy sent a reporter to ask people if they voted to see if they would lie about it on camera to make themselves look good.