How to Break-Up With a Bank Teller

I decided, if I was ever dating a girl who worked as a bank teller and I felt like things were starting to go south; I would preempt the break-up by sending a dog turd in an envelope through those pneumatic tubes (yes I did just Wikipedia the technical name) at the drive thru.  I've always wanted to do something like that and I think it would send the intended message.