Inverse of M-q, an unfill-paragraph-function

Question

Is there an inverse for M-q, some kind of unfill-paragraph-function?

If I have undo data, then it\'s of course easy. What I am asking for is

Answer 1

See also M-^ (delete-indentation).

It joins the current line to the previous line, so if you start with point at the last line of the paragraph you can keep pressing M-^ until all the lines are joined up.