You call up your best friend and say, "Hey, I'm moving on Saturday, come over and help me." Your friend either says "Sure, I'd love to" or "Sorry, got a hot date, catch you at your housewarming party."
Ironically, Ask culture is usually used in transactional settings where you barely know someone, Guess culture is usually used in smaller community settings where you have a lot of personal context, but Tell culture (which is a level beyond Ask in directness) is usually used in intimate settings where you have a strong bond with someone - either family or very close friends. At that level of intimacy, it's expected that someone can say no to a direct request without hurting the relationship. It's the same reason close friends frequently make fun of each other or horse around in mock physical combat - it demonstrates that your relationship is strong enough that insult doesn't hurt it.