The Chronicles of Sheldon Mayer's Sugar & Spike
Sugar & Spike #8 
Reprints: None (yet)
Dedication: Wayne Posz (age 8), Indiana
A classic look at the eternal failure to communicate theme that the series featured, this time the kids put some clues together and realize that their parents don't actually understand their baby-talk. Naturally their solution is to try to teach them, starting with the easiest word they know, "GLX", meaning "Hello". When that doesn't have the result they expect, they attempt to reconcile the various reactions they get to the word to figure out what it means in grown-up talk, but their perfectly logical conclusions only get them in more hot water.
Lervly story, especially the baby logic, and some wonderful expressions on the kids. This also features one of my favourite S&S scenes ever, a bit where Spike helps Sugar escape from her playpen "prison", only to wind up in it himself, with the final reveal that they can just lift it up and get out anytime. Throwaway bit that isn't even referred to in the dialogue, just a cute visual to enjoy on a second level to the main plot.
Characters: Sugar, Spike, Mrs. Wilson, brush salesman, various neighbours
Damage: Many, many dishes, a fruit bowl and a plant
Punishment: a sentence in the "pokey" (a playpen) and various trips to the corner
"I think that when we're talking good, clear baby-talk to them, they think we're just making silly noises that don't mean anything!"