to freeload for long periods of time in a residence which is not your mother's. To not realize you are an inconvenience and are actually disillusioned to think that because you've found a semi-permanent place to couch surf and/or guest room snatch, you're now fading into the background and the residents forget you're there, when, in actuality, you are the splinter in the household's thumb. They may not always be able to see you, but your presence is irritating and the longer you stay, the more you fester.
To fail to recall something you have previous knowledge of only to realize you had the knowledge after it is explained to you. Usually followed by an "OH YEAH!"
Topher's Friend: "Didn't you see that movie?"
Topher: "No, that was someone else."
Topher's Friend: "Remember? You spilled your drink all over the people in front of us."
Topher: "OH YEAH!"