When someone gets someone else in trouble, basically snitching. A 16-year-old girl does it a lot to her assistant teacher, and sometimes, one of her friends is involved. This happens a lot at the Summit Upper School in Queens, NYC.
Kira: He did it!
Charlie: You just threw Eric under the bus!!!
Kira: He deserved it though. Serves him right for not dancing!

Throwing someone under the bus is sorta funny…
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