Used in long uses of exclamation marks, the !1one is an intentional mistake that jokes about the appearance of numeral value "1" in exclamation overdoses. This is due to the shift key not consistantly being pressed while tapping "1" for the overused "!"'s. The intentional error may signify even more exclamation marks, like some kind of lunatic scientific notation. !1one may= !E9 or !*10^9, thus representing an absurd amount of exclamation.
It's typed when someone thinks that s/he can be funny, and since you press shift and 1 when youwant to make a ! symbol, if you forget to press the shift, a nice 1 will appear. But there's no point in typing the whole "one" word, however.
Someone that wants to be funny: LOL !1!1one!
The one who will pwn the guy who wants to be funny: Wtfh does !1!1one! mean?
The first guy: Look at the definiton -_-