I've played quite a bit of the latest entry in Croteam's twitchtastic first-person shooter series, but I never encountered the super-speedy giant unkillable pink spider creature in the first level. Know why? Because my copy isn't pirated.
In order to curb rampant pc game piracy, developer Croteam purposefully included a bug (hee) in Serious Sam 3: BFE that trips when the game has been cracked. The bug (I said it again!) spawn a pleasantly-pink, positively unkillable scorpion creature that will hound the player until he or she is dead, dead, dead. To give the pirate a fighting chance, the spawn point is right next to the game's first projectile weapon. It won't have any effect, of course, but you'll briefly feel better.
While not a particularly effective means of combating piracy, the giant immortal pink scorpion is a fun way to catch those masquerading as legitimate customers in places like GameFaqs.
Thanks for the entertainment, Croteam!