Internet Amnesia
That moment when you open a new tab and are about to do something - then you totally forget what you were doing.
Person 1: I was mindlessly wasting my life away on Tumblr so I decided to open a new tab and OH SHIT WHAT THE F*CK was I going to do.
Person 2: Shit, you must have internet amnesia.
Person 2: Shit, you must have internet amnesia.