So I've tried this before and its pretty hard.. so I decided to share it. This is very similar to the Runaway Teen Challenge.. except is way harder.
I'm sorry if im copying anybody

Recommended town: Moonlight Falls
You dont have to play here. Its only recommended

Rules:
-No adopting (must be a biological mother)
-Do not make the child in CAS (it has to be a baby and u cant really make that in CAS)
-Cannot make a shelter
-Lot has to be a 10x10
-The only thing in your lot must be a sleeping bag/ bed
-Only steal 6 things a day
-Must be very close to your baby/babies
- Baby must learn how to walk and talk
-Setting must allow sims to age

Goal
The goal is to raise as many children as a homeless teen mother before growing old and without any of them dying or getting taken away by a social worker

Mods You Need
First off, you should a mod that allow teens to WooHoo with each other or with young adults/ adults. There are plenty out there.
Also, get a mod that allows you to disable curfew (once again, many mods out there)
Then, get a mod that allows households to have teens without young adults/adults/elders
Lastly, get a mod that allows teens to get pregnant

Create A Sim
In CAS, you CANNOT make her very attractive. Just make her average. SHE MUST BE A TEEN GIRL! You have to make her look as realistic as possible. A realistic hobo. Try to make her have ripped up clothes. Also, you cant put makeup on her. Try to make her hair ugly and messy. If you cant get that then put it in a ponytail.
-No makeup
-Not pretty
-No fancy clothes
-No pets
-She cannot be a supernatural

Traits
You must have these traits:
Kleptomaniac
Slob
Brave
Family-Oriented

Name
The name must be:
Destiny Hill

Actual Challenge
Move in to a 10x10 lot. Place down a sleeping bag. If you dont have a sleeping bag, get a bed. Then, set your familyfunds to 0. After that, go to edit town and bulldoze your school so that your sim wont keep on trying to go to school. Then, find a guy that your sim is attracted to and become best friends. Once your best friends, start being romantic until it gets up to the Try For Baby point. Then, Try for a baby . Keep on trying until you get a baby. The baby must be named with the same last name (Hill) . If you dont have any money you can earn by stealing things (klepto) and selling them. Remember, dont steal too much. Only steal 6 things a day.


Well... you get the point. So, good luck!
If you have any questions/ concerns, please feel free to post something

Why does the name have to be Destiny Hill?

You can only steal 3 things a day. I dont know if there is a mod, but I know there is a limit. You can steal more than 3 things if you stay in a house after 12am, but then you cant steal anymore until next day at 12am. If there is a mod, (andthere probably is, because there is a mod for almost everything) please post it.

Just looked, I believe this might be the one:
http://modthesims.info/download.php?t=392602