UFC Fighter: Busted In Voting Lie ... On 'Jimmy Kimmel'

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 Tuesday night.

Kimmel was doing his "Lie Witness News" segment -- where he goes out to bust people lying about voting on Super Tuesday.

The setup -- 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.

Ellenberger fell for it ... hook, line & sinker.

Ooops.