How to fail at a job interview

Currently looking for a job, but not exactly anxious to began working again. I already had one interview at a telecommunications company, which didn't go well. I didn't dress that professional wearing my favorite paint smeared hat, an underarmour sweatshirt, and khakis. Not really wanting the job I impatiently wait for my interview seriously thinking about bailing. I finally get my interview from a easygoing young man not much older. The interview questions were basic, and although not giving much of a care I maintain an amiable conversation. I didn't really answer the questions that well, but didn't make an ass of myself yet. After only about five questions and a little chit chat its seems that hes considering me for the job to my surprise. Then I decide to ruin any chance after not answering the last question well by saying "I'm sorry I'm not giving a good interview, I've just been having a bad day." Apparently these idiotic words were the demise of any chance of employment. Two weeks later after wondering if I ever was going to begin training I receive a letter informing me that I didn't get the position. Back to the drawing board.