It is possible to make a bunk bed on EA's The Sims 2. To do this you need to do a glitch. You can find the details online.
If your Two sims are in Romance level (You know this if your sims can Make out) get both of your sims to relax in Bed by clicking on the bed and press Relax. Make sure both of your sims to do it. Then click on the sims you want to Woo Hoo with and press Woo Hoo or Try to have a Baby
in the sims 1 for the PS2 you can have a baby, have two sims make out few times or have them both relax in a bed and select "play in bed" if you have the sims 2 for the PS2 then you can't have kids.
Get a mod. that's much easier.
You can find in the Buy Mode.
Make sure both sims are in love, then get them to relax on a bed. Click on the Sim you aren't controlling, and select WooHoo.
You have 2 sims relax on a bed adn have them try for baby
you get your sims to love each other then go to the bed and click, relax. then click on one of the sims and click try for baby.
Get both of the sims in the bed relaxing and select one of the sims that is laying in bed then click on the other sim and select cuddle.
You can have babys on sims 1, but you can only make them on the love bed, and the social worker comes alot, I prefer sims 2 & 3.
Make them go to a bed and relax then click on one and say woohoo:)
You press the bed, and I think you are trying to make them woohoo, so press relax. Then press Woohoo or Try for Baby to have sex.