I was playing Morrowind and ,you know, they had this little sound effects like *grumbling* or *sniff* or *clears throat* at random times.
Once I sniffed and the very same split-second my character made the *sniff* sound too
![laugh](emoticons/beigelaugh.gif)
Not sure if this could be considered as "weird" but it sure creeped me out
Another really weird bug was while playing sims 2. Random..objects...were....spawning... EVERYWHERE! (they filled the attic almost completely)