The phenomenon by which an individual becomes aware that this is not the first time they have forgotten the same piece of key information.
Arsenio Billingham: Dude, what is that's chick's name again, the one with the really fat head?
Gary Kasparov: Man, you asked me that last month.
Arsenio Billingham: Whoaa, I just got the biggest dejamnesia
When a person does something outrageous while inebriated, then dosen't remember it the next day.
You were so wasteds you almost got in a fight with a guy twice your size! You wouldn't stop hitting on his girlfriend! You got damnesia, because I was like DAMN when I saw that!!