Pregnancy Announcement - Image #852,181

When you think about it, it makes too much sense.

Goku ended the cell ark by doing a suicide boom with cell (and there was some story reason as to why he wasn't instantly brought back), and he left behind a second little child to remember him by.

This pic uses Dragonball Z Abridged style logic to theorize that Goku did the suicide thing and chose not to be rezed because he didn't want to deal with a 2nd kid. Which, again, going by DBZ abridged logic, makes absolutely perfect sense since he had already seen what Chi Chi was like during pregnancy.