Minecraft 1.10.2, Minecraft 16w32b
I was messing with a new world in creative mode and I equipped a shield on my off-hand, and a golden apple on my main hand. Then I hold right click and the shield wiggles for a split second.
I think it's supposedly a smooth blocking animation.
And it wiggled. (wiggle wiggle wigg, bala ba ba bala, wiggle wiggle wigg)
1. Put a golden apple on the main hand
2. Put a shield on the off-hand
3. Hold/Spam right click to see the wiggle
p.s. sorry for not uploading a video/picture