fun governor

Someone who must make sure to quell or stop activities that would be viewed as fun by others (usually due to general laziness, jealousy, fear or lameness).

( a name usually assigned to wives )

can be shortened by calling the guilty person an "F.G.".

Someone who has to be in control of every situation and is a total buzz kill at times. Believes if he/she is not having fun then no one else should either. Known to be somewhat contradictory and hypocritical at times.