They think so.

“I think so.”
“See, that's the problem. You can't respond ‘I think so' every time someone asks you a question.”
“Let me rephrase it... What was the question again?”
“I have to go soon.”
“Why?”
“Run errands.”
“All right. Well, I can't answer if you're not asking anything, can I?”
“You didn't even let me finish! As I was saying, I have to leave soon. Will you walk with me?”
“Where?”
“That's another problem.”
“What is?”
“You. Responding to a question with another question.”

“Actually, I keep repeating that I think so, but in fact I don't think so, I know so.”
“That's what I thought.”
“No, that's my point. That's not what you thought, that's what you knew. Besides, do you think so just because I think so?”
“What the... No, the fact that I think so has nothing to do with you thinking so out loud just a few seconds before I thought so out loud!”
“So what, we both think so?”
“I guess I think so.”
“Fine, let's think so! Let's say so! Let's do so!”
“You're weird, do you know that?”

“ I think so.”