This comic is from Berry’s World, written by Jim Berry. It appeared on June 11 in 1970.
Berry’s World, June 11, 1970
While the joke does not revolve around bare feet, we can see that bare feet were the style of the day (and that “style” helped contribute to NSNSNS signs).
Ahcuah 
Now I wonder, was it more common in 1970 to be barefoot in one’s own kitchen than it is today?
At least this young man isn’t violating the “no shirt” clause 😉