As they say, there are two rules in improv: Never say no, and never ask why. When another actor asks 'Why?' or says no to something you're suggesting, then it's very clear that they're putting the onus on you, because they're not comfortable with it themselves.
“I gave my parole once, and it has been shamefully violated by the British Government; I shall not give another to people on whom no faith can be reposed.”
“I have been working, as emergency relief coordinator, on an international scale, very hard to build a wider alliance of partners in assistance efforts.”