I looked at 3 plugins to add ASCII art to your WordPress blog. This is the first one, Kilroy Was Here, which I loaded up and experimented with. It does work but may not be the results you wanted.
There are no options to add the ASCII art to the bottom of your posts or pages. The plugin does place ASCII art at the very bottom of my site, under the footer. The spacing was out, the lines between text. Also, the top line of my art was pushed to the left.
I tried another ASCII, thinking a longer image would look better either way. Adding HTML code worked to keep the formatting but, it shows up on the site.
Still it is nice to have a little surprise for anyone who reads to the end. So I will keep this plugin and see how often I remember to change out the ASCII art images.