burn down
1. To destroy something with fire. We watched helplessly as our house burned down despite the firefighters' efforts.
2. To weaken or wane, as of a flame. Get the birthday girl in here—the candles on her cake are burning down!
3. slang To embarrass someone (who can be mentioned between "burn" and "down"). Andrew must be really insecure because he's always trying to burn other people down with snide comments.