Someone who often allows a small electronic device, a computer mouse, to substitute for interaction with the real world.
My friend seldom bothers to answer his phone any more...too much effort, he says...he's turned into a real mouse potato with his like-minded Twitter and Facebook friends..
Potatoe is an older but still correct spelling of the word more commonly word spelled potato. It turns out that Dan Quail and the young student were both correct in there spellings. The e at the end of potatoe was largely dropped by the end of the 20th century.
Like teabagging, the man is dipping his testicles into the mouth of either an unsuspecting (usually sleeping) victim or into the mouth of a partner for sexual gratification. The distintion between teabagging and potato sacking is that only a man with extremely large testicles can pull it off.