I use the word "inappropriate" when in that type of situation. I find it comes off better than "what a stupid idea" or "you've got to be kidding me" or "what, were you raised in a barn or something?"

btw, sorry that I dissed Angel, but I was hoping it would provoke a response. Like I said in my LJ, I don't know much about Angel, except I thought that "ANGEL: 1943" was a reference to the year he was born..