You're doing a lot of work to get the correct index for your array. Since you know the string's length is going to be even, could you try to make the step in your loop i + 2, rather than i++?

Why are you interpolating the 2 in your regular expression?

string.repeat(repeat)

:D

think this is along the right lines, but you've got quite a lot of unnecessary code in it. You could strip most of this out and it would still work.

you can stick puts tweet on the first line and see it on the console at runtime.