Unintended loneliness

My boyfriend's brother and three sisters are over at our house right now. I love them all dearly; however, at times I can't help but feel a little left out. They don't mean to do it, but they'll start speaking Portuguese (their native language) and they'll forget to translate for me, the lone American in the room. I try not to be offended... But it sucks when everyone in the room is laughing at a joke except for you. It's like they have some secret club that I'll never be a part of...