var sketch = context.api(),
  document = sketch.selectedDocument,
  selection = context.selection

function randomIntFromInterval(min,max) {
  return Math.floor(Math.random()*(max-min+1)+min)
}

for(var i = 0; i < selection.length; i++) {
  var layer = selection[i].frame()

  // RANDOMIZE X POSITION
  // var currX = layer.x()
  // layer.setX(currX + randomIntFromInterval(0, 5))

  // RANDOMIZE Y POSITION
  //  var currY = layer.y()
  //  layer.setY(currY + randomIntFromInterval(-10, 10))

  // RANDOMIZE HEIGHT
  // var currHeight = layer.height()
  // layer.setHeight(currHeight - randomIntFromInterval(0, 30))

  // RANDOMIZE WIDTH
  // var currWidth = layer.width()
  // layer.setWidth(currWidth - randomIntFromInterval(-20, 20))
}