You can buy juice in bags here, I guess it's cheaper than using cups.

Also, when you buy 40s (caguamas), stores make you leave a deposit for the glass bottle, usually about 20 pesos or so. My friend told me that there was a trend that lasted for a summer: everyone would ask stores to put the beer in a plastic bag, as a way of avoiding the bottle deposit. I like thinking about trends that exist in just one place for a small amount of time.