There seem to be two meanings of “unexpected” not being differentiated here:
1) name-derived terms like Debian, or the French ‘poubelle’ in the comments, which have become genericized to the point where most of its users don’t know the derivation
2) a more interesting subset of (1), like PageRank, or Lake Mountain in the comments, where part or all of the name itself looks like a normal word appropriate for the situation. (a related concept is nominative determinism https://en.m.wikipedia.org/wiki/Nominative_determinism)
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.
For further reading, here's the blog post that named the concept: https://www.lesswrong.com/posts/rEBXN3x6kXgD4pLxs/tell-cultu...
And further discussion within the same community: https://thingofthings.wordpress.com/2015/05/08/against-tell-...
There were a bunch of tumblr posts on this as well which are more work than it's worth to go recover.