It means that I want to say same thing as someonle else said (in this case what #2 said). But instead of Ctr+C, Ctr+V on his text (which would be rather noob'ish) it's more "poilte" to say something like I said in my last post here...
For more info read this:
http://www.urbandictionary.com/define.php?term=i+second
That still doesn't change the fact that it's shit.
Note that the coins don't actually do anything, and are actually more challenging to avoid than to collect. What a horrid game.
For more info read this:
http://www.urbandictionary.com/define.php?term=i+second
Holy *beep*