Moonwalk

To anxiously backtrack, alter or offer excuses to a previous statement, argument, or action that has suddenly been proven to be flawed or otherwise false, without ever truly admitting why it was as such. Usually the hallmark of someone who cannot stand/afford to be proven wrong.

"When Joe finished telling Jane where he was last night, she revealed the proof to the contrary. Dumbstruck with the confrontation, Joe nervously attempted to moonwalk his way out of the situation."