Alien abduction

Alien abductions is an event that can happen in both The Sims and The Sims 2 when a Sim stargazes at night through a telescope. Their motives go haywire whilst they are on board the craft, and they return a few hours later.

The Sims
In The Sims, an abductee will simply return with a different personality.

The Sims 2
In The Sims 2 if the abducted Sim is male (and adult or older), he will come back pregnant 100% of the time and give birth to a baby, with the unseen NPC Pollination Technician. To be abducted (or have a relative abducted) is a want for Knowledge Sims, and a fear for others.

If you have the Nightlife Expansion Pack, you can also be abducted if you dance fast in the Dance Sphere with ten Body Points.

In FreeTime, all of the telescope actions have a chance of alien abduction, but the Aspiration Reward for Knowledge, Summon Aliens, has your Sim create a spotlight with a flashlight and telescope, with a huge chance of abduction.

Aliens are very important to the Strangetown story (especially with The Curious Brothers), and play a lesser part in Pleasantview except in the case of one Bella Goth.

If you want a Sim to be abducted, use the "boolprop" cheat, then shift-click any telescope, and then select be abducted.