[eigencoder]

To get a 32-oz soda, wouldn't you just have to go to a gas station?

[thaumasiotes]

A gas station? No, they'd be selling prepackaged sodas in the 20-oz size.

You might be able to do it at a 7-11, since they sell empty cups that you're meant to fill with a slurpee. I don't know if they also have soda fountains to fill those cups.

[parineum]

You can't buy two 20oz sodas at a gas station in the UK?