I third that - You throw this out when you're not just agreeing, you're mak

You throw this out when you're not just agreeing, you're making a statement, and you're probably gonna argue about it later.

I third that, and if you don't believe me, I'll prove it with my middle finger and a napkin.

I third that, and I'm not even tired. This song is the best, and you're a disgrace.

I third that, and I'm gonna text you at 3 a. m. to remind you.