Legolas calling Gimli “Meleth” simply because he doesn’t know what it means
Legolas getting so used to calling Gimli that that when they go for a visit to an Elven kingdom, he forgets about his kind’s extremely sensitive hearing and says it in a hallway or something
An elf hears and just drops everything they’re holding and runs to inform the king
Legolas and Gimli getting called to a meeting which is really just an hour-long shouting match in Elvish
Gimli having absolutely no idea what is going on
After Legolas explains, there’s a heartfelt, teary-eyed acceptance (also in Elvish)
Gimli still not knowing what’s going on at all
And then THE EXACT SAME THING happening on their visit to the Dwarves when Gimli fucks up and calls Legolas “Ghivashel”.