I guaranteee it.

From now on, I'm going to start every endeavor by saying, "I guarantee disappointment." 

This way, if I let you down, I've lived up to my promise, and you can't be angry.  Conversely, if you aren't disappointed, I've failed to keep my word, so I've met my guarantee.

This is either win-win or lose-lose; I'm going to say its lose-lose, that way you can't say I didn't warn you.

You're gonna love this suit.