Yeppt: Ask questions that expire.
Yeppt is the fastest way to get definite answers from your friends:
Pose a question. Set the countdown. Get quick answers.
Every question has an expiration date: "Are you coming to the cinema with us?" expires latest when the movie starts. Every Yeppt-question includes the expiration date in form of a countdown (which helps you prioritize by indicating the urgency of the message).
Answering a Yeppt-question with "No", deletes the thread. No more spammy messages from non-relevant topics. Answering a Yeppt-question with "Yes" leads to a group chat where all yeppers can settle the details.