Just to get to the point that SNS Glitch is actually known as "SN Glitch". But most players on private servers refer it as the SNS Glitch.

SNS stands for Special > Normal > Special

I'll give a brief explanation how this works.

To activate this glitch, you will need a slicer (most likely Charge Diska Hot +50 or Diska of Braveman Hit +40% or Slicer of Fanatic). Next, you need to face a mob of enemies (as long they're not lizards or Ill Gills), then use the Special Attack. Before the Special Attack lands, use the Normal Attack and the accuracy becomes 100%. And now for your next attack will also have 100% of accuracy.

Special Attack (Accuracy of 60% roughly) > Normal Attack (Before the Special Attack lands, Accuracy 100%) > Special Attack (Accuracy 100%)

This works very well with most slicers.