How do you get this cool exhaust popping noise?

Having an open exhaust system will cause it. For instance my car it has a straight pipe with a 21 inch glass pack only, and it does it when I shift or let off the throttle sometimes. Also echo tips help amplify the sound.

Exhaust Pops

It is usually caused by a lean idle mixture. Old cars with carburetors you could adjust the idle mixture on the lean side. New fuel injected cars it almost requires an exhaust leak up near the head to simulate this. I think an exhaust leak makes it sound trashy compared to a good sealed system with a glass pack. My 1976 Mustang Cobra 5.0 liter has older (true) duals with glass packs and large diameter pipe near the rear. Sounds great, but no popping on deceleration. If I screwed in the idle mixture screws it might.

that's called back fire. exhaust back fire usually caused by a restriction or ignition timing. it can be caused by exhaust flow headed backwards in the exhaust from it bouncing off bends that are not mandrel bent or the dimples in a glass pack or "fart can". In other words its caused by the way certain exhaust restrict airflow. Not having back fire is a good thing tho. Also ignition timing can create it by not properly tuning the vehicle and pouring unburned or partially burned fuel through the exhaust which causes that fire ball out the tail pipe (destroying the CAT) can cause as much damage as a misfire to the exhaust. causing excessive carbon monoxide, hydro carbons and nitrates of oxygen as well as destroying the o2 sensors.

The only way to make a backfire noise that I know of is to have the engine timing off a bit- It is unburned gasses in the exhaust system that ignite and create this backfire noise- NOT RECOMMENDED- It could blow your mufflers up.

Your bowl of rice is trying to tell you it hates the fart can and ridiculous wing on its back.

You had it right, it's a pooping sound.