I was standing at a street crossing, and two girls(about 14 years old) ride up saying "分かりますか?” "分かりますか?” ("Understand?")
I wondered what they were asking me I understood, so I said "日本語で?" ("Japanese"?)
That got a chuckle out of them.
If I was in America and I saw a Japanese person, I wouldn’t ask them if they knew English, I would just assume that they would.