first, enter the collective unconscious through one of the brain tumblers located either in agent Niens lab or the dome where it all started, once inside head to holly's level at the door that looks like this:

enter the level and select "hollis' hot streak", as seen below:

once inside turn to your left and look for this little guy:

now walk up and take a bubble over to the maternity ward, just like so:

once in, look behind you and find these floating thoughts:

grapple through all of them and get on top of the hallway, where at the end you'll see a large dart, just like this:

last but not least, use telekinesis to pull the dart out of the ground and aim it at the neon sign saying "ward". Once you're sure it will land you can fire it, and watch as the Easter egg plays before your eyes in all its glory. You don't have to jump down like i did but know that if you miss or break the dart you will have to exit the mind and start this guide from the start.

hopefully if everything went well you should have been able to watch this hilarious and strange video made by the good people at double fine, attached below is a no commentary video guide, and below that is just the pregnancy video itself if you don't want to see it in game. I hope this guide was helpful and worked well for you