This strip looks a little familiar to me, like I've seen another strip like it, and recently.
A lot of this strip depends on technique. The punch comes from Patty's setting up the reader for expecting an actual medicine with a fancy, scientific name in the third panel. It's all but required that they be multi-syllabic words, so Charlie Brown can foil those expectations in the last panel with his single-syllable retort of "Glue!"
