The act of walking home from a party or other social event where one has drunk too much and committed embarrassing acts, rather than that waiting for or asking for a ride. Often done clandestinely (i.e., without letting your friends know you left).
Usage: Shameabout can be used without an article, in the same way as safari or sabbatical (i.e., "on shameabout")
Partygoer #1 - Hey, where did Rick go?
Partygoer #2 - He had a few too many and started fondling the hostess with a soup ladle. Then he serenaded everyone with a rendition of "The Fat Boys Are Back" and threw up on the new sofa. I think he's on shameabout."