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.

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, and play a lesser part in Pleasantview except in the case of one Bella Goth.

There's also another way to get abducted, using the "boolprop" cheat, then shiftclick any telescope, and then select be abducted.