An IOD is a signal displayed by a girl which suggests she is not interested in you. These signs are often pretty obvious, such as being ignored, or a girl not stopping to talk to you. More subtle IOD’s to look out for are things like; she doesn’t give much of a response when you are talking to her, or she only gives one or two word answers to your questions. Often when this happens, the girl is trying to be polite by answering and responding to you, but is giving you very little by way of a response in the hope that you will notice her lack of investment in the interaction and leave of your own accord.
Another common IOD you might find is that when attempting to number close, she will object and offer her facebook instead. As before, she is giving you her facebook as a token gesture of kindness. If she was really interested she would have given you her mobile number, which is a more private and personal mode of contact. That said, sometimes a girl just prefers facebook, and just like with IOI’s, some IOD’s may not be IOD’s at all. The key is not to become disheartened by IOD’s – find the funny side to them and move on to the next girl.