Alien abduction

Alien abductions is an event that can happen in The Sims, The Sims 2 and The Sims Bustin' Out 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 unless the abductee has the knowledge aspiration and WANTED to be abducted to begin with, 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. The odds of being abducted are very low, on the order of 0.05% percent for each animation cycle.

If you have the Nightlife Expansion Pack, you can also be abducted when you dance fast or medium in the Dance Sphere, if you have already been abducted once, even if you were a teen when you were abducted the first time. Each Dance Sphere will only trigger one abduction, but the odds of abduction are much higher than with the telescope.

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 Bella Goth and the Caliente Family.

If you want a Sim to be abducted, use the "boolprop" cheat, then shift-click any telescope, and then select be abducted. This cheat dosen't work when Seasons or Bon Voyage gets installed. It also will not result in the Sim having the memory of alien abduction, but will still result in pregnancy for male adult Sims more than 6 days from Old Age.