The Suite Life of Zack and Cody/WMG

Carrie has a brain tumor
This is evidenced by the World of Warcraft parody eouside where she claims to have a "Virtual Headache.... no, no wait, it's a real one.
 * Because giving her son money for a virtual game, only to find out he had bought it himself isn't worthy of a headache?

London doesn't know how many times her father's been married
In one episode, she says twelve; in a later episode, she says eight. Given her ignorance of so many other things, and that she and her father barely have a relationship, this is the most logical explanation.

London's mother wasn't Wilfred Tipton's first wife
He's been married either twelve, fourteen, or eight times, Depending On the Writer. London's charm bracelet only has five charms, one for each stepmother. It's highly unlikely that Tipton was married six times in less than a year (it takes time to fill out all those papers), so this is much more likely.
 * Part two of the Suite Life on Deck special "Twister" confirms her mother as his third wife.

Wilfred Tipton is immortal
He's been married numerous times (not that that couldn't happen if he was mortal).

More to the point, he also founded Tipton Industries. Back in the 18th century, during the planning of the Boston Tea Party, there was already a Tipton Inn on the same spot that the Tipton hotel is currently on. And the current Tipton building has been around since at least the 1930s. London's father, if he was of average age for a father, wouldn't have been around to see to the building or creation of that new Tipton; and if the Tipton Inn was the direct precursor of Tipton Industries, then no modern mortal could have both started that and been around in the present...

Maybe he's so incredibly old that it would be emotionally scarring for anyone to see his face. That's why he covers it.


 * Sadly we are lead to believe that London's father is only a descendant of the original Tipton.
 * Recently has been jossed. In the new "Twister" episode we see Wilfred Tipton's face. He looks like a normal 40 year old person.
 * Doesn't joss the entire thing, though. Just the part that he has a bajillion year old looking face. He could be immortal without visibly aging much.

Kirby was a beer delivery guy before he joined Tipton Security
To see the video evidence, look under on the main entry in the On Deck section under Hey Its That Guy Seriously, the dude looks, talks, and acts just like Kirby!

Cody is a Goa'uld
Zaria was a minor Goa'uld (with the ego of a System Lord) who ruled a small dominion in South America. In the episode "Can You Dig It?", she was released from the preservation jar in which she hid since the overthrow of Ra, whereupon she possessed Bailey and attempted to reestablish her reign. When the rest of the Suite Life gang had her cornered, she pretended to return to her jar as per the Tau'ri superstitions. In reality, she possessed Cody, trying to remain incognito. Nevertheless, her genetic narcissism shines through, resulting in a neurotic, egomaniacal portrayal of her host, seen by all observers as a twisted parody of the Cody they once knew.

Tutweiler's "Cat Room" doesn't contain cats
The real reason she wanted so desperately to keep Bailey and London out of there is it contains her extensive and eclectic collection of sex toys (which is what she really buys after getting dumped.) Woody found one that had somehow made its way outside the cabin and, not knowing what it was, disassembled it to build his turkey leg rotating device.

The S.S. Tipton has its own cell tower/satellite uplink
How else could everybody's cell phones work everywhere?

Chelsea Brimmer's parents are divorced
When Chelsea's dad was convicted of tax evasion, her mom divorced him and married Chelsea's equally-rich stepfather. This explains how Chelsea is still filthy rich despite her dad being in Federal prison, in which case the IRS would likely have seized his assets.

Cody abuses Bailey
I thought this WMG up when I was reading the domestic violence article on The Other Wiki and got to the signs and symptoms, I realized the only part of the cycle of violence Cody and Bailey weren't outwardly showing was the violence part, and that could be chalked up to the fact it's Disney. The fact that Bailey doesn't show any signs of abuse after the (unseen) fact could be due to, as mentioned above, the fact it's Disney, or it could be due to the fact that Cody may not be abusing her physically. In other words, Cody's abusing her in one of the following ways: sexually, emotionally, verbally, economically (implausible, but not impossible), or by stalking her. He's most likely emotionally or verbally abusing her or stalking her, probably stalking. God, is there evidence that he's an intimacy-seeking stalker (or perhaps an incompetent suitor) in obsessive love.
 * There might not be "outward" signs of violence, but Cody has on occasion showed signs of, ah, creepiness that align with your theory: in "The Play's The Thing", he killed Bailey's Expy. In "Prom Night", he wrote "drop dead, Bailey" on his voting slip just because she wasn't paying him much attention at the prom. In "The Defiant Ones", he very swiftly and severely kicked Bailey in the ankle to provide an alibi for himself when Bailey wasn't cooperating. He was also a massive jerk to her throughout most of "Beauty and the Fleeced."


 * Is it me, or is this twisted fanfic material?

Cody and Bailey lost their virginity together the night before "The Defiant Ones"
It would take something of that magnitude to make Cody miss a homework assignment. The reason Bailey went along with the whole injury shtick, even tolerating Cody actually injuring her, was she wanted to deflect any further inquiry into the matter. The level of angst post-breakup is also consistent with having taken that step.
 * Considering their conversation about Bailey "faking it" (laughing, allegedly) this makes sense. However, it may have not been Bailey's first time- Moose has made her "laugh" before. (See next entry I just added)

Bailey had sex with Moose and then with Cody
This would explain Cody's obvious discontent with her in Paris, about her "shaking her bonbons," as he probably assumed she slept with the french guy. This also goes with their "faking it" conversation, as she was probably Cody's first, seeing as he was a "geek" barerly going through puberty when the spin off started, and Bailey was already a beautiful girl. Either that, or Moose and Bailey fucked when she was in Kettle Corn after she and Cody broke up.

London is constantly held back in school
In "My Sister's Keeper," it is said that Zack and Cody have known London for six years. Since she was 15 at the start of The Suite Life of Zack and Cody, which was when they first met, London would currently be 21 years old. She could have been held back so much that she ended up in the same grade as Zack and Cody, but never noticed because of her stupidity.
 * Confirmed in "Prom Night", when Ms. Tutweiler tells London she can't run for Prom Queen at the Senior Prom more than three times.

Stephane was impaled on the Eiffel Tower at the end of "Breakup in Paris"
When Zack and Woody land on the Eiffel Tower with Cody, Stephane follows suit. Zack and Woody believe that it's an "Eiffel Tower Wedgie." I, for one, found the sound effect illustrating that a bit...gruesome. Also, following Stephane's "wedgie," he can't be heard saying anything that would suit a sitcom villain like him. No, "I'll get you kids!" Nothing. Just eerie silence. Now, how could Zack and Woody mistake a horrifying death for a goofy outcome? It was nighttime. It was dark. They don't seem too bright anyway. It was an honest mistake.

Sebastian from Party On! has a tapeworm
How else could he eat all that chocolate and not be severely obese?
 * Excersize? He seems to move around a lot whenever he's on screen.

Project Gemini will someday be uncovered
by Alphabet Soup their attempts to replicate the project result in Gem and Gemma. this even explains their names.

Zack have reunited with Maddie after the series finale
Since Zack and Maya didn't repair their relationship, it's undeniable that he still loves his "Sweet Thang". The graduation episode didn't say or show that Zack reunited with Maddie, but it could be a hint that he did. In fact, many Zaddie fans consider it that he had returned to Maddie after this episode, for both of them to fulfill each other's promises, despite Maddie not being able to keep her promise to Zack about the prom part. If Ashley Tisdale returned in this episode, the episode would have been a bit more better.

Getting London through school was the only reason Seven Seas High existed
Wilfred Tipton was at his wits' end after putting London through every private school in Boston, Catholic school, and even public school. As a last resort, he created a program for her in which she'd be in close quarters with (relatively) normal kids and thus be forced to learn social skills, and to see the world from their perspective. The "employee discount" that enabled Zack & Cody to attend was a full tuition waiver, since Tipton knew they had some influence over London. With London's graduation uncertain, and the boat failing to turn a profit, Tipton stood ready to abandon the whole enterprise. Fortunately, London rose to the occasion.

In "Family Thais" Zack and Girl of the Week Hilary had sex
She wasn't going to be around and born those of them seemed to be trying to get laid (with each's other wingmen, both who were in relationships)

Mr. Mosby is related to Jeffery from The Fresh Prince of Bel Air
Their personalities are close enough that Mr. Mosby could easily be an Expy of him.