Got any ideas for revenge?

So my former best friend stole my best friend's (who also happens to be her best friend too) boyfriend. Then she goes round boasting to her friends about how she's gotten eaten out be the boyfriend, and how shes now gone the furthest then the rest of us have. We're not suppose to know, but I found out, and now I want revenge on behalf of my friend. She is TOTALLY for the idea of revenge and she will never take the boyfriend back. There's NO WAY I or my friend will ever forgive the ****** that stole her boyfriend, so being happy for her is out of the question. The revenge has to be humiliating/hilarious, but can't reflect badly on my friends or me. Thanks for reading ^^