'Teen Mom' Star Farrah Abraham -- Pathetic Excuses For DUI

"Teen Mom" star Farrah Abraham just admitted to drinking and driving before she was busted for DUI last week ... but she's convinced she's done NOTHING wrong.

The 21-year-old called in to TMZ Live moments ago with a litany of ridiculous excuses for getting behind the wheel under the influence last week ... you won't believe how delusional she is.

TMZ broke the story ... Abraham was arrested in Nebraska on St. Patrick's Day night -- after blowing a .147 on a breathalyzer, nearly twice the legal limit.

And don't forget those crazy pics of her partying back in January ... drinking from the bottle and kissing chicks ... she knows how to get down.