Double Downie

Someone who continues to do something in an even more determined way than before.

The term is used as a euphemism when someone tells bald-faced lies and when confronted with contradictory statements, he/she not only fails to retract their claims but instead expresses an increased certainty in their truth.

Derivative from double down - a term used in the cardgame blackjack where someone doubles their bet in a risky situation.

"Instead of just coming clean about his falsehoods, Bradley decided to double down on his lies in the hopes of convincing others he's telling the truth. Bradley is doing a Double Downie."