inverted slay

inverted-slay (noun)
/ɪnˈvɜr.tɪd sleɪ/

Definition:
The opposite of a "slay"; something that is not good, successful, or desirable. Often used humorously or colloquially to describe an action, event, or outcome that falls short of expectations.

Amber: that woman who lied about flying a plane is a liar. She is definitely an inverted slay.