I’ve been to drive thrus with 3 stages, speaker, payment, food. So I think what could happen is you go to the payment stage, tell the teller you want to pay for the person behind you, the person behind orders at the speaker box, you’re still at the teller so they can charge you for both, and then give you both receipts. You then go up to the food box while they’re at the teller box and since the food box is just told what to prepare, you show them both receipts and get both meals.

I might be misremembering, but I think it’s technically possible.