No...

One of the first rules of improvisation is to never say "no"...for instance if your stage partner says "would you like a pickle?" you are supposed to say "yes" to keep the action moving...If you were to say "no" then the action would end... there is nothing left to do except argue back and forth... not very interesting for the audience or the actors...I am also a firm believer that this rule carries over into life... saying "yes" will keep things moving and shaking in your life...obviously there are times when you cannot possibly say yes or when it would put you in danger...but as a general rule... i think yes is generally best.