Holiday Amnesia 

When you forget about presents you bought someone for Christmas. Usually occurs because gifts were bought after Christmas or in the summer when they're not as expensive

Mike: Where'd you get that new skateboard? It's June.
Jim: My mom found it in her closet. She said it was from last Christmas
Mike: She must have suffered from Holiday Amnesia

Holiday Amnesia by J_F7 January 3, 2010

Holiday Amnesia 

When you return to school from holidays and completely forget what you learnt the previous year.

Guy 1: Wow, I can't remember ever learning differential equations last year...
Guy 2: Yeah, we must be suffering from Holiday Amnesia

Holiday Amnesia by Manbearpig911 March 13, 2012