These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
As well as everything involving the Scout's "ballsack" in Teen Fortress 2 (weren't it for The Half-World, one would assume she meant a sack containing baseballs).
Skepkitty, who runs The Half-World, hadn't yet read the next chapter which makes this more clear (he MSTs stories as he reads them). He chose to go with the crazier interpretation partly because it seemed somewhat plausible after what Rattman did with the personality cores in It's My Life, and partly due to Rule of Funny.
As well as "CHAPTER SEX". Rule 34 can apply even to chapter titles.
The strangest of all comes from "J an Ks Wubulos Adventure" where J and K fight a Super Mutant in Portal High School's bathroom. Why the mutant was there, what it was doing, or even how it got into the bathroom in the first place, is never addressed.
Crack Ship - THE MARRISSA GAMES has Prim/Peeta all over itself, but there are also pairings like Gaz/Demoman and Medic/his mom.
Mary Sue - So let me get this straight, not only is this character somehow Chell's sister, but she also has New Powers as the Plot Demands, is the daughter of Caroline and Cave/"Gabe" Jonson (despite somehow having a different last name) and had Wheatley's "robot ball/human" child she called Chell after the original was killed once and for all. Somehow. Even though Assirram (Marrissa's evil clone) made an "abortion". And even after Marrissa died and was resurrected in process.
Instead of being chosen or volunteering in the Reaping, Marrissa is personally called to the Games by President Snow himself.
Thirteen Is Unlucky - Depending on how you look at it, Chapter 13 of ITS MY LIFE!. Factually, Marrissa is resurrected and Assirram is created. The Half-World takes Marrissa's resurrection as a sign of the most Mary Sue-ness an OC can get, and Assirram becomes the main antagonist of ITS MY LIFE!.
Also, if it weren't for the Oracle Turret, in Chapter 13 Wheatley would have committed suicide.