Bad is Good

When did language twist to allow the word bad to imply something is good? Or sick to be something good? After thinking on this a bit, I decided that it could be a full comic strip. However, I did not know which words I would use until I started. And even as I created the final "punch line" panel, I changed it to use the words fly and whack. My original idea was to have Mr. Green use skidoo and Mr. Blue to say something about Green not saying what he meant.