The Moving Goalpost

A logical fallacy that attempts to discredit the opponent's position by asserting the opponent's failure to act consistently in accordance with that position. It attempts to show that a criticism or objection applies equally to the person making it.

Tu quoque

A method of denial that involves arbitrarily moving the criteria for “proof” or acceptance out of range of whatever evidence currently exists. The goalpost can keep moving back if new evidence Occitan that meet the criteria in order for it

Meaning "You too", aka "Two wrongs make a right."
B. Essentially stating that your error can be overlooked or disregarded, because others have
committed the same error.
C. You can't accuse me of libel because you were just successfully sued for libel.

Ex: Bella Donna claims that Sybil Antwhisper, her room-mate, is not sharing the housework equitably. Sybil tells Bella to go away and itemise and record who does what household tasks. If Bella can show that she does more housework than Sybil, then Sybil will mend her ways. A week passes and Bella shows Sybil clear evidence that Sybil does not "pull her weight" around the house.
Sybil (the advocate) responds: "That's all very well, but I have more work and study commitments than you do – you should do more housework than me... it's the total work of all kinds that matters, not just housework."