Someone just lets out a shout of agony, when feeling extreme sadness.
This is a redo of an old ykttw. Some characters get so emotionally distraught that they can't even let out their feelings in words, so they just let it out in a scream. This is usually to help punctuate the drama of a moment, to show that's it's dire enough to bring one character to this point. This is why many works use this rarely, to avoid ruining the serious of the moment. Works that overuse it can turn into Melodrama. Although it can also be Played for Laughs, but even then is still usually reserved for the right moment. Often, this can overlap with Inelegant Blubbering, Berserker Tears, Unable to Cry (when this becomes a substitute for tears). A Sub-Trope of Angrish. Compare Big "NO!", Gasp, Manly Tears, Tears of Remorse, The Scream.