I am in no way endorsing the use of a carboy as a serving vessel, but for the sake of science, let's discuss this.
Pressure = Force/Area
A bottle explodes when the pressure of the interior exceeds the pressure of the exterior. Because the interior surface area is the same as the exterior surface area, we can also say that a bottle can explode if force acting on the interior of the bottle exceeds theft force acting on the exterior of the surface.
So now let's look at priming. We prime in order to create CO2 to carbonate our beer. The CO2 molecules are created and add to the force acting on the interior of the bottle. Assuming a proper priming (even sugar distribution in the correct amount), you would essentially create 50 or so miniature carboys with the same interior force.
...and now I realize the flaw in my logic. Theoretically, if I would then combine all of this force into a single vessel (carboy), the area would not increase proportionally to the force, increasing the interior pressure.
TL; DR: DO NOT PRESSURIZE A CARBOY.