I found a short sample of myself, i played it backwards, and it sounds like the word marijuana. At the end of the sample you can hear it really clearly.
A cacophony of frogs recorded in a marsh near the coast of north carolina. You can hear the squeak of bicycle brakes as i rode into a particularly loud spot.
There was a giant swarm of cicadas, and i recorded them. You can hear the individual ones that are close in the background of millions of ones in the distance.