The latest I saw said “If you think your English is good, I challenge you to write any word that starts with T and ends with T.” Others I’ve seen are just as easy and have just as little need for good English. Interestingly, the comments (i.e. answers) number in the millions. But what’s the point to these? Seems unchallenging and useless to me.
To make you click / share!
Clickbait. Making people think they are smarter than everyone else guarantees lots of responses.
Okay. Who benefits from all these clicks/responses and how?
It’s all part of Big Data. The people who put these challenges up can compile lists of the usernames of those who took part in them, and sell those lists.
Advertisers would pay for lists of Facebook users who are active enough to click on semi-random stuff like the challenges. I understand that the type of challenge they click on can be correlated to various particular tendencies of that list of people, useful for targeting a desired demographic. This can have applications far beyond straight advertising.
Back in the day, you’d see a lot more of this. Facebook, at the time, was set up (via a loophole) so that people would create groups and start lots of these “which do you like more, Like for green, comment for Red” type things. After a few months they would sell the group to a business based on the stats. The new business would rename the group and already have a built in fan base.
Years ago, however, facebook closed that loophole, at least partially, and you can no longer change the name of a group after it has a certain amount (1000?) of followers.
As for nowadays, I assume it’s just money. Either the person creating the original post is getting paid for clicks or they’re getting their likes/comments/engagements etc up and then getting money to post ads.
In any case, I always cringe a little when I see those things. Especially the easy ones. If a post bets you can’t name a state that starts with A or a word that begins and ends with the same letter…there’s a reason for it. They don’t actually think you can’t answer, but every like/dislike, comment, share etc all benefit them somehow. Even if you don’t know how, it’s probably better in the long run to just ignore it.
Perfect timing. After posting I went over to facebook and the first post I saw was one of these. A friend had responded to a poll asking if we call an everyday item by one name or another name. One of the names is a regional thing and very few people around here would use the other name. As of right now it has hundreds of comments as well as plenty of likes and shares. That means that hundreds (thousands, even) people that don’t like or follow that facebook page will see it and may start following it. From there the business will gain more followers and have a larger group of people to advertise to.
It’s just as common as a local food store to put up a post along the lines of “We just got in these new super sweet orange bell peppers, what would you do with them” and comments will pour in. The store doesn’t care, they just want the comments because it makes other people see their page.
I’ve seen the same thing happen on food blogs. That one drives me batty. I’ll be looking for a recipe, click on one because the little snippet I see in the google results says “4.2 stars, 310 comments”, but when you I go to the page, maybe one or two people actually made it and commented on how they liked it, all the other people commented because the blogger raffled off crock pot to the people that commented. All the activity moved the post up to the top of the google results.
It’s also a bit like evolution. These “easy challenges” might not be the best or the most purposeful clickbait, but the only actual criteria for going viral is whether or not people interact with something.
People that don’t pass the easy test get put on a list of people to spam with phone calls and offers from Nigerian princes with larger amounts of cash to transfer. 
You are helping them build personality profiles on yourself when you participate in these things. First is you are the type of person to say OK to taking these things. Then they get to test you. Then they can target you better for advertising.
Most people don’t know the top 10 points to these challenges. Number 7 will SHOCK you!
That’s a slightly different category of clickbait - the slideshow one where the list is presented in a list with some kind of teaser reveal towards the end, one entry at a time, with ads being displayed for each entry. Thus guaranteeing at least 7 ads getting hits (validated screen time) en route to that SHOCKER at #7! (And hey, if #7 was so surprising… What could #8-10 be like? LET’S FIND OUT!)
The ridiculous challenges like “bet you can’t name a city without an A in it!” is just to get people to share the link to show how smart they are, and buried in the link is of course an ad of some kind, or some 'bot that adds you to a mailing list.
Ever hear from anybody who took an online IQ test that did NOT score 133?
I found one yesterday that gave me a measurement of 0x190 and I elect to believe they were working in hexadecimal instead of the alternative.
There’s another type of scam where you agree to share your facebook data (photos, friend lists, whatever), in order to see what kind of monkey you are, or whatever. People didn’t realize that playing these games would allow the game developers to use the facebook API to hoover up a whole bunch of your personal data, and in some cases even the personal data of your friends.
Yet another type will have you answer a bunch of personal questions like your pet’s names, or where you come from, in order to ‘personalize’ some stupid horoscope or prediction or career choice or whatever. This data is extremely valuable to hackers who can use it to socially engineer hacks or engage in identity theft.
Facebook: Just say no.
It’s a lot less than 1000. I ran my national guard company page and when the Army changed our designation I tried to rename the page and they wouldn’t let me. There were only a couple of hundred on the page.