Meat Boy/WMG

Meat Boy is a Time Lord
Yeah, another one of these, and one indication is the constant reincarnation upon dying.
 * He's an interesting anomaly among Time Lords. Not only is he on something like his 6,000th regeneration, each regeneration is exactly like the last one!
 * Apparently the result of regenerating too many times isn't a Critical Existence Failure for your ability to regenerate after all. You just staart losing fine bits of data and degenerating into something simpler (and easier to reconstruct). Meat Boy must have died an awful lot before the game even started, but since he has nowhere left to fall death has nothing to scare him with.

Lil' Slugger (the phallic chainsaw robot that is the game's first boss) is a remnant of the HHHHHHHHHHHHHHHHHHHHHHHHHHHHHH universe.
Giant groinsaw? Check! The soundtrack "rocking the fuck out"? Check! Everything covered in flames and destruction? Check! This theory speaks for itself.

GLaDOS is responsible for creating Dr. Fetus as well as Meat boy and Bandage girl
Meat boy is similar to Atlas and P-body in terms that he is a robot made for testing purposes (albeit an organic one) Seeing how meat boy refused to do the tests, G La DOS invented Bandage girl as a goal at the end of each test, and Dr. Fetus as the means to keep the tests going indefinitely. In the intro cutscene for "Teh internets" as Dr. Fetus is being assembled by mechanical means, you can see G La DOS' silhouette in the background, giving birth to Dr. Fetus as we know him. Right after he wakes up, she plays a Laugh track to taunt him, and make him bitter torwards everyone. Further things that make this plausible are the precence of portals in World 4 and the Headcrab as a playable character.

Bit.Trip is about human life...
And Meat Boy is in Bit.Trip as Commander Video's friend. Meat Boy maybe represents the emotional development and romance of a long term relationship, overcoming struggles and childish fights (symbolized by Dr. Fetus).