Non-Americans; do you have trouble understanding spoken American English?

[Gaijin]

I know what you mean. Well, I only speak Swedish fluently, but my brother said something to me once in English, and I replied in Swedish. Probably because I was having a heated conversation with a Swedish penpal on MSN at the time.

lol I have a story like that. A friend of mine speaks 3 languages, English, Spanish and Chinese (Dad's Australian, Mums Spanish, lives in China for work) and when he was younger he would get tired and just start speaking other languages to me and then you could see he was grumpy that i wasn't replying until he realised I had no clue what he was saying.

Yes that is exactly what sometimes happens to me...
For example when once two nice ladies asked me and my friend to explain them a route to some specific place, they asked on english and because I understand english very well it was as they asked in my native language (serbian), and I started explaing the way on German... lol
It this situation there were 3 languages in speech, but for me it was all like we were talking serbian only. After I realised that they don't understand me I started talking English.....
With the speed of parsing words and translating them inside your mind, you tend to start on the language you speak better or often, simply because your brain translated it faster.

There are also few stories that Bilingual people tend to have split personalities! Which I can approve....

Now it also happen to me to start thinking in Programming languages I know, and express that way, leading the people who listen feel like... w0w....