Where to buy a subway ticket?

One of my British friends (from my hometown, Fukui) was staying at the K's House a while ago. He, my K's House co-worker Megu, and I were drinking beer and having fun chat.

Someone brought up this topic: At the K's House, there come many tourists who have never lived in Japan before. What has been the most annoying/damn question you got by the tourists at the K's House?

There are many. There are many questions that the tourists ask other people before they even think by themselves.

Here is a silly one.

A tourist: "Where can I buy a subway ticket?"

...You see, the answer is obvious!!! A subway ticket is sold in the subway station!!! Is there any country that you have to buy your subway ticket at a supermarket?! Or a drug store, or a pub, or a Starbucks cafe???!!

Here's another silly one:

A tourist: "I'm thinking to take a subway to go to Shibuya now. How much does it cost for me to take a subway?"

...ahhh!!! You see, you just put your shoes on, walk to the subway station, and you will see on the giant price list at the subway station. It's not a mystery!