animate.css/source/attention_seekers/rubberBand.css

@keyframes rubberBand {
	0% {
    transform: scale(1);
  }

	30% {
    transform: scaleX(1.25) scaleY(0.75);
  }

	40% {
    transform: scaleX(0.75) scaleY(1.25);
  }

	60% {
    transform: scaleX(1.15) scaleY(0.85);
  }

	100% {
    transform: scale(1);
  }
}

.rubberBand {
	animation-name: rubberBand;
}