Can you guess this sound for R50,000?

Martin Bester has a brand-new Secret Sound, and one lucky listener will win R50,000 if they can correctly guess the sound. Listen to Breakfast with Martin Bester every weekday from 06:00 to 09:00 to see if you can guess the next sound. To enter, all you need to do is SMS 'Secret', your name, and what you think the sound is to 37942. SMSs are charged at R1.50. T's and C's apply!