In the case of a thing:
Anything which is unnecessarily added onto something; used especially when such addition impedes the full functionality or greatly increases the expense to obtain it. The object itself may be frivilous if it is unnecessary in it's setting. See SUV.

In the case of an action:
To deliberately go through a large amount of time and effort to achive significantly less result than what was justified for the effort. See Rube Goldberg.