digital hangover
n. Feelings of shame and regret caused by social network photos and other online evidence of one's embarrassing behavior.
The drinkers admitted waking up to find friends had uploading videos and pictures of their drunken behaviour. And 16 per cent recalled asking friends to take down the offending material — for fear their families or employers might see.

The phenomenon — dubbed a 'digital hangover' — has increased thanks to the popularity of Facebook, Twitter and the spread of camera phones.
What seems to be going on here is that Facebook users going through their timelines cannot believe that they, in the past, said certain things in public.

They are having a digital hangover from their wanton youth.
—Nicholas Carson, “Facebook Has A Festering, Global Problem With No Solution,” The Business Insider, September 27, 2012
2005 (earliest)
Colin’s friend e-mailed the photo to his workmates, who printed it and plastered it all over their offices. It zoomed via cyberspace to friends of friends, ended up on a few blogs and even Friendster.

His lousy, liquor-induced headache only pounded harder as he suffered what might be called a digital hangover.
—Mary Huhn, “Texting under the influence,” The New York Post, April 21, 2005
A very slightly earlier example is Rebecca Miller's A digital hangover from April 13, 2005, although it refers to next-day regret from having drunk-dialed.