A Spoonful of Sugar

Make sure that when inserting foreign objects into player characters that you have enough henchmen to hold them down.  Nothing is more frustrating than when a player rolls a successful dodge vs. insertion. Wow, that sounds totally inappropriate. 

Back Against the Wall

Players sometimes get a god complex where they think they are untouchable.  Making your players powerless for a short time and having your way with them drags them back to the reality that their players live at the GM’s whim, and you don’t mess with the GM.

Crossroads

 Sometimes GMs are the embodiment of evil.  We just tell ourselves it’s for the good of the game, to make it more believable, if we have trouble getting to sleep at night.