'Suffice it to say.' is incorrect because it's not a sentence, there is no subject. 'It suffice to say.' is an incorrect tense of the verb; it should say, 'It suffices to say.'
Many things could be said, such as:
"Nothing." Repeat what has been said. "Yah..." "I didn't say anything." "Your face."
All either have to do with the previous sentence just spoken, or the person...