Question about modeling of Popping water balloon

I would also say that Rhino/Grasshopper may not be the perfect tool for the task.

However, have a look at Flexhopper, which you could be used to simulate and spread fluid droplets and splashes:

The splash simulation is part of the Flexhopper examples.

Simulating the cracks in the ballon surface seems to be a very complex problem and would require a crack simulation (e.g. using XFEM).

If you just want to create these ballon patches, then one approach could be to create a simple mesh sphere, deform it and remove different regions of faces using very edgy curves.

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