The state of unpleasantness that follows a night of heavy binge drinking. The effects of a yesterfester can include but are not limited to the following:
Beer Farts, Headache, Beer Shits, Puking in one's own bed, Lost articles of clothing, personal items or friends, Heartburn, Nausea, Indigestion, Yay Pepto Bismol!, Feelings of Helplessness, Waking up to a toothless woman or dude, being lost, and losing your identity.
Part of the overall experience of a yesterfester is piecing together the events of the previous night that lead up to the yesterfester. Yesterfesters are often the result of a yesterfest.
Brian: Oh man I have a terrible yesterfester!
Scott: Yeah you called me and asked if your new homeless friend could sleepover last night.
Brian: Did he?
Scott: Yeah he's upstairs making breakfast. You should really give him something to wear.
Brian: Well that would explain my sore butt hole. I feel like shit.
Scott: Sounds like you have one hell of a yesterfester.