It is the sound of something falling.

It is used to mention that something or someone has fallen.

Burukudlu fase ka disego… – I’m down on the floor with laughter.

😂😂😂😂😂😂😂😂….burukudlu on the floor..m https://t.co/NuoJrxhH39

— Bereka_Mosadi (@remo_poeng) October 27, 2016