Needless to say, I wasn't a happy camper.

不用说，我当然就不高兴了。

If you're not a happy camper or you're not a happy bunny, it means you're not pleased with the situation.

如果“你不高兴”或“你不开心”，这表示你对这种情况不满意。

Meanwhile, your brain isn't a happy camper either.

与此同时，你的大脑也不是一个快乐的个体。