So, how do I buy a cola?

I have spent a good amount of time gawking at Nostr and the posts going on there - with all the zapping and whatnot. Think they just hit a millionth zap or something?

Anyway. Whenever I hear people talk about crypto, I just walk away. Because so far, whenever I read an article about the usecases of Bitcoin or anyothercoin, it is filled with "[could] be used for". But "could" is not "can".

So, I would like to ask here: How do I buy a Cola with bitcoin?

Imagine that all I have is an Android phone, a few Euros in my bank and an absolute thirst - right now. What do I do to pay with Bitcoin to buy me that Cola?

(I know the described situation is a little extreme. Basically, I want to know the fastest, most "convenient" way it is done. Not could - but can.)