Was trying to buy nitrous oxide capsules for a handheld espresso machine today in New York.  I went to a shop and in my UK-affected speech pattern asked the assistant for “bulbs to use with a whipped cream machine, which look a bit like the CO2 bulbs you’d use with a soda syphon”.  After a lot of head shaking and gesticulating, he said “Oh! You mean like the gas cartridges for a seltzer bottle?  I think we have those!”