Open Hay Day and go to your farm
Tap the Shop button
Open the Decorations section
Look for the Pig Ghost decoration
Check the Seasonal or Halloween category if available
Buy it with coins or diamonds if it is in the shop
If it is not in the shop, wait for a Halloween or special event return
Check the Farm Pass, event rewards, or seasonal offers
Look in the roadside shop or special event catalog if the item is offered there
Place the Pig Ghost on your farm after unlocking or purchasing it