Just yesterday, i called h on this. I forget what we were talking about, something serious, and he laughed. I said, "Don't laugh at me!!!" He said, "I didn't laugh." "yes you did! just now, you laughed at what i said!". I walked away into the house. After he left, he sent me a text, "I would never laugh at you." And 5 minutes later, "Nerves". IDK if he meant nerves as in he is nervous around me, or mistyped, never. Doesn't matter. Weird. I didn't respond.
From another perspective, I know my teens, especially the two that are awkward socially, do laugh at inappropriate times, especially in their early teen years(13, 14, 15) So this may be the reason our teen MLCers do it. IDK.