Want a steamed bun or dim sum, ma'am?"

It's a question often asked at the check out in 7-Eleven convenience stores in Thailand, just as you're about to pay your bill.

In Russian grocery shops, there are no steamed buns or dim sum.

But there is a standard question, delivered whenever you pay for your purchases: "Want a bag, ma'am?" And if you say "yes", it means you'll have to pay for it.

I really don't understand why they're so stingy about plastic carriers. But, looking at it from another angle, it makes people see the value of bags.

A bag to carry your shopping home costs at least 1.5 roubles (Bt2.25). You pay more if you want a better-quality tote.

When I first arrived in Russia and didn't know much about the place, I said "yes" every time and received a bag - which I then had to pay for.

Now with more experience, every time I go shopping I take my own bag along, so when I'm asked if I want a bag, I can say: "No, thank you. I already have one." Then I sweep my shopping into my bag and feel happy to have saved at least three roubles.

Bussaba Piwkam is a student at St Petersburg State Pedagogical University in Russia.