Looking for a Good Riddle!

Hello everyone, I have a favour to ask and this seems like an excellent place to do so.. I am looking for a riddle with rather specific characteristics, but have been unable to find a suitable one so far through my internet searches. It seems the members on these forums have a bunch of experience and must have seen many examples of excellent riddles so I kindly ask for your help. the characteristics are:

1. It has to be simple to understand (not complicated with many lines that require a lot of thought and re-reads).
2. It has to be no more than 4-5 sentences.
3. (most importantly) it has to have a subtle, one-to-two word answer which seems obviously correct, but is not correct.
4. It has to be as compelling as possible; people should want to give it a go!
5. It should be as "unknown" as possible (ie not turn up in your first internet search)

I guess, essentially, it has to be a trick-question of sorts. The purpose behind the search for this ideal riddle is for a very good cause so I would appreciate any help you could offer!

Thank you in advance- your assistance is much appreciated!