This particular image exists nowhere in any one comic.  The sources are actually four different images put together.  The reference to ‘pouring’ is an art world in-joke.  It refers to Morris Louis’ brand of modern painting, using poured paint. Lichtenstein delighted in the double take.  “Okay, hot shot, okay!  I’m pouring!”  Was this Lichtenstein’s humorous answer to the critics who attacked his work?  Was this his tongue in cheek reaction to others insisting that if he were making real art, he would be pouring the paint on the canvas to make nonobjective designs?