Thrown under the bus

[Donald Trump]

To intentionally reveal damaging or unflattering information about anothers character or transpired event, while at the same time trying to make themselves look good or innocent in the eyes of the listener. To shift blame or attention in a cowardly way.

[Sonia]

Phrase made popular by a small town graphic designer in northern Michigan after watching two battling chipmonks attempt to hurl one another under a fast moving shortbus. Denotes an individuals willingness to sacrifice anothers future and recognition for ones own gain. Blatant disregard for anothers well-being. Betrayal.

[Britney]

To be thrown under the bus; A popular term at Boeing and possibly other corporate entities.
When someone either intentionally or unintentionally says something that makes you look bad or points out a mistake you made in front of your peers. This is similar to being backstabbed, but usually the circumstances are much more minor. This is sometimes used jokingly to tell someone that what they said may have crossed the line, or they were stepping on your toes.