Lisa Is Pregnant

A Simpsons fanfic in which Bart and Lisa are trapped on a snowy mountain, and forced to have sex in order to stay warm. Bart dies after exhausting himself keeping Lisa warm, and Lisa survives, but is pregnant with Bart's child, which she decides to have out of respect for Bart. What.

Notable for the completely awful spelling and grammar, as well as bizarre syntax and word choice that make it seem as though English is not the writer's first language. These turn what would otherwise be fairly Squicky into something that is quite laughable.

The fic, found here, is currently three chapters long, but is either discontinued or ended.

Tropes used in Lisa Is Pregnant include:

Artistic License: Biology: The whole "recess recieving organs" and "dominant 'worm'" business.
- That, and the fact that she found out she was pregnant the same day she slept with Bart, unless she was asleep for a long time.
Blind Idiot Translation: The fic often reads as though it was translated from another language (?Bart was the right!?)
Brother-Sister Incest: Bart and Lisa
Dead Fic: Has not been updated since the third chapter, with Lisa still waiting for the birth and still not remembering why she and Bart were on the mountain in the first place.
Dramatic Reading: Here and here.
Dumbass Has a Point: Homer asks the fairly good question of why exactly Lisa was on the mountain, which the narration notes is more insightful than usual for him. Lisa can't remember well enough to answer, though.
Easy Amnesia: Lisa forgets much of what happened on the mountain.
IKEA Erotica: Bart is merely described as undressing Lisa and rough(ing) her up.
Intimate Healing: Attempted, although it only saves Lisa because she doesn't have to exert herself.
MSTing: Here.
Out with a Bang: Bart.
Retcon: Arguably revealing Bart and Lisa as older than in canon, since it was never suggested before.
Rouge Angles of Satin: More than a few times, particularly "wood" replacing "would".
Smart Ball: It's lampshaded when it's said that Homer noticed "for once".
Someone to Remember Him By: Invoked in the debate over whether to let Lisa have an abortion. Marge sees the baby as the only living part of Bart, and Lisa agrees, noting that she will have him out of respect for Bart.
Teen Pregnancy: Word of God has it that the fic takes place a few years after the main setting of The Simpsons, when Bart and Lisa are (biologically) old enough to have children, and Maggie is able to speak and understand the concept of death.
Time Skip: See Teen Pregnancy above; the fan fic eventually says that it takes place after the time of Simpsons, toning down the squicky-ness of Lisa getting pregnant with Bart (although not by much) and explaining why Maggie can talk. However, this isn't until two chapters after the aformentioned pregnancy.
Too Dumb to Live: Bart and Lisa play on a snowy mountain in their normal clothes. It also doesn't occur to them to light a fire, although it is possible they didn't know how or didn't have any resources at hand.
- Even then, they could have simply hugged each other. Also, wouldn't being naked in the mountains make them colder?
Troll Fic: Some reviewers think this might be one.
You Answered Your Own Question: "Who is father? And why was Bart found on top of you and inside of you and naked and you were seen in a suggestive lovers pose with him with your panty accidentally loose?"
You No Take Candle: The fic lapses into this at times. ("You awake. Bart is D'oh")