Whats the word for someone who forgets things a lot?

I just remembered (thanks to facebook reminders oddly) that its la mere's bday on Wednesday...and i have done fuck all about it. SHIT. What are you two doing?? I have no present for her, no card, nothing. I mean, admittedly last year she sent me a present in July when my bday is in March, but still. What are we gonna do??? Es could you get her something from me and then I'll pay you back when you get out here?? Help!