When you are sitting on the toilet and someone comes up and flushes it before you are donepooping. You then can feel a moist breeze on your nuts.
Everything was coming out just fine until she sneaked up and gave me a Tropic Thunder from Down Under. I was unable to get off the toilet since I was not finished dropping my load. The cool breeze did feel nice on my balls though.
An Australian Aboriginal man wearing nothing but a pith helmet who dances on your table and sings "Land Down Under" if you order a "Chocolate Thunder From Down Under" at an Outback Steakhouse.
If you order a "Chocolate Thunder Down Under Deluxe", you are taken into a small, unfurnished back room of the steak house, where the man will leave you to fester in fear for a few minutes, then pop out at a random time and sing "Land Down Under" while wearing nothing but a pith helmet.