Have you ever seen a balloon look like this after it's popped?

I came across a question on reddit asking why balloons sometimes pop in that particular "sine wave" pattern. I have seen the pattern myself multiple times, so I looked for science papers that would explain the phenomenon. The few papers I found didn't really come up with an explanation, though they did rule things out.

They concluded that:

1) The air in the balloon didn't matter (they were able to replicate the effect by just stretching the material), and

2) It was unlikely to be a defect in the way the material was manufactured (they tested multiple materials in multiple directions)

Heres a fun theory that I think is worth sharing:

I would think that there's a stress line in the rubber, and that when the 
balloon first breaks it breaks slightly above or below the stress line.
The break then tears towards and then past the stress line, oscillating back and forth 
because the pressure on the side of the break that is closest to the stress line
is greater than than the pressure of the side of the break that is away from the
stress line.  The reason it doesn't just stop on the stress line is because there 
is an extra bit of stress that is generated from the rubber's elasticity being
released that is sometimes greater than the stress that's coming from the difference
 in pressure, depending on where on the sine wave you are.

Here is a picture of the forces for visualization purposes: