system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why exactly are those gurgling sounds our stomachs make?

Why do stomachs make the sounds when we're hungry?  After we've eaten?  
If you put your ear next to someone's stomach, there are countless, unique sounds that it makes...but none of them sound like fluids sloshing around like you'd hear in a water bottle.  So what exactly are we hearing?
gpt
When you're hungry, it's called the migrating motor complex (MMC) - it's basically 'house-keeping' to move bits of roughage and fibre out of your intestines and to keep the whole system clean and tidy, without bits of old food sitting around. The sound you hear when your stomach growls tends to be from it vibrating while empty, the vibrations making the sound, and this is the start of the MMC which continues down to the end of your digestive tract.

When you have eaten, signals are sent to the brain to start normal peristalsis (intestinal movement) to move the food along, and the gases in your intestines plus the liquid-y food content (fluid having been added through pancreatic and stomach secretions) being squeezed through the intestines makes the sounds. It doesn't sound like sloshing because it's not uncontrolled movement, the food is literally being squeezed and the spurting of liquid and sudden movement of gas through a tight constriction causes the gurlging sounds.

I hope this is useful!