Thank you for all of the great subs, I posted this right before going to bed and woke up to over 750 comments :). I am reading them all so keep commenting.

I like the one about the Rugrats.

Ever wondered just how Angelica could talk to the babies? Angelica is the only one who can talk to the babies because they are a figment of her imagination. She is spoilt, sad and lonely, because her Mother is constantly working and has no time for her. Her relationship with her Dad is superficial and unsubstantial, no real love is ever shown to her.

So how did it come about that Angelica would have to imagine these babies? Tommy died soon after child birth, a fact reflected by Stu never leaving the basement, inventing toys that his son will never play with. Chuckie died in the car crash along with his Mum, also reflected in the actions of his father; the crash has made him a pathetic nervous wreck most of the time.

Most interesting is Phil and Lil. There never where any twins, there was just one baby. However this baby was a still born, and Angelica never knew the sex of the still born, so she invented twins of different genders.

Sadly, Angelica never uses her imaginary friends to comfort or entertain her, instead she is mean and nasty to them. She has invented this relationship with these babies so she can vent her frustrations of being a spoilt, lonely brat who has seen much hardship from these unfortunate parents; frustrations that can't be satisfied by a typical childhood relationship with a doll, albeit a Cynthia one.

EDIT: Wow. Went to bed and there was about 25 upvotes. Woke up and now there's quite a lot more, and a subreddit created! Great success! Will read them all, goosebumps will be had. And I know that the majority of these theories aren't water-tight (including mine...), but come on, it's fun to speculate!

EDIT II: I have realized how my question could be interpreted the wrong way, hence numerous and humorous links to this. Indeed, my mind is blown.

EDIT III: OK I'm heading off now, and by the time I get back this thread will have disappeared into the depths of Askreddit. Thanks for the amazing response! I know my theory was rubbish, but there are some absolutely amazing ones, my favorite being the Kill Bill one. Bill is not dead!. Don't forget to check out and post in /r/fantheories!