It was introduced on 1st of April and was definitely on the frontpage for few days.

They also have a blog post [1] about it.

[1] http://www.redditblog.com/2015/04/the-button.html

To be honest, you don't read reddit daily :)

> What is the button?

> The button is a feature that the popular social media site Reddit introduced on April 1, 2015. It has its own subreddit at /r/thebutton.

After April 1st it hasn't been that visible though

Button-related posts keep making it to /r/all, though (my main Reddit window).

There was a blue box on the right side saying "Have you clicked the button?" on most subreddits I read on April 1st.

Most likely, he is blocking ads

It wasn't an ad. Adblock did not affect the "have you clicked the button"...button.

It was definitely an ad[0]. But the Reddit subreddit ads I think are excluded from Adblock Plus if you have it set to allow "unobtrusive" ads (which is the default)

[0] http://www.reddit.com/r/ads/comments/3181or/did_you_press_th...

Not the button I'm talking about[0]. There must have been ads too, but there was a generic non-ad "Did you press the button" button on the front page in the days following Apr 1[1].

[0] http://web.archive.org/web/20150402105722/http://www.reddit....

[1] http://i.imgur.com/Hvn6AuG.png

it was announced in a blog post, and has featured many times on /r/all, but if you don't ever read /r/all, you wont have read it.

It was also most likely featured at some point on trending subs. And if you read a hell of a lot of reddit, you'll see it mentioned elsewhere on the site (like in memes, comments etc)