Comeuppance.

Overheard in New York | Don't Make Me Go All Forte on Your Ass:

"Snobby woman to teenage girls talking: Decrescendo, girls. Do you know what that means? It's an operatic term for 'lower your voices.'
Teenage girl: Actually, 'decrescendo' is a musical term for 'get softer,' and when you say get lower, you're actually referring to pitch, not volume.

--Metropolitan Opera Lobby

Overheard by: Maria"