Mithro
'Mithro' is an adjective, used to describe somebody who excessively trolls, and will claim the opposite of what you say they did.
"Jake is being a Mithro, he keeps saying he did not say 'Supercalifragilisticexpialidocious' but the whole chat saw him and even screenshotted him saying 'Supercalifragilisticexpialidocious' yet he still denies!