Suefic

A Suefic is a story, often a fanfic, in which the main character is a Mary Sue. More than that: the story revolves around the 'Sue. Often, there is no plot beyond the 'Sue finding out about all her uncanonical powers and falling in love with the character that the typist thinks is the most attractive.

Alternately, a Stufic contains a Marty Stu who generally finds out about all their uncanonical powers and how they save the day in the most awesome way the Stuethor can think of.

Most, if not all, Sue and Stu fics are written by young writers. They are essentially daydreams written down.