So, a Burr's Corner is when an actor in Hamilton makes a mistake on stage, most of them being forgotten lines. I saw one in the 10th anniversary OBC reunion performance of Rent.

This is what happened:

Mark:... We light candles.

Roger:.... um.... uh.... when on every street [A/N: That's not YOUR line, Roger, it's Collins']... nope...what fire...stuck in your flue!

That was hillarious, and the audience was cracking up.