Posted by Max Ashton on November 14, 2006
I could not find the idiom "throw your hat in the door" using Google and Answers.com, nor on your site. I was trying to check that it means what I think it means.
Back in the old days, and it would not be a bad idea for some in these days, when a man came back home after being away for a while, he would throw his hat in the door before entering. If it was thrown back out, he knew that he was not welcome. If it stayed in, he was home free (another idiom).
I think of it as seeing if you are welcome or not.