title: Insert rows into random places in pandas dataframe
body: <p>I have a very large sample dataframe (~640,000 rows), and I'm currently testing to see if a parser I've built can detect specific phrases. This dataframe is full of text strings. </p>
  
  <p>I'm trying to find a way to insert a specific number of rows into random places within the dataframe. </p>
  
  <p>This the basic structure of the dataframe:</p>
  
  <pre><code>                                            Comments            code  
  0  The stupidity of it is that gamed to total def...            NaN  
  1  called poker face she s actually...                          WP  
  2  Example not identifying the fundamental scarci...            NaN  
  3  No tol is bait That s the point...                           NaN 
  </code></pre>
  
  <p>The imputed rows have the same structure as the rows in the dataframe. </p>