the one where I lack people skills

Yesterday afternoon I was messing around in my kitchen when someone knocked on my door. As this has never happened in the two years I have lived here I almost fell off my chair. Then I jumped up and looked for a hiding place, realizing I was being totally irrational I then answered the door. It was my neighbor and the following conversation ensued:

Neighbor guy: "Hey, some friends are over making me dinner for my birthday and we need a cup of flour, do you have some?"
Me: "Happy Birthday!"
N" "Thanks"
Me: (sad voice) "Oh, Pearl Harbor day, bummer."
N: "Yeah..."
Me: "So I don't have any flour 'cause I have Celiacs"
N: ....
Me: "But I am making cookies soon, I'll stop by and give you some for your birthday."
N: "OK, sounds good"
Me: (firm) "I'll see you later then."
N: "See ya."

Needless to say I totally forgot to bring him cookies. This is why I don't speak to my neighbors.