Mazes!!!

No, you have to build a maze. Most likely a GP would be too smart to bother trying to figure it out and end up yelling at you until you just gave it the darn bait at the end.

An energetic pig might do it, but I don't think it would do much more than stress them out and make them confused. Mazes are better for pet rats and mice.

Yeah... a piggy would probably feel trapped and freak out, where as rats are like, 'OMG, WHAT COULD BE AROUND THE CORNER?????!?!?!?1" and mice are going, "I wonder if there's a way to get out down here..."

Piggies are a lot like very timid dogs, I believe, kinda. They won't get near you unless they recognize you, they like to gnaw/nibble on you if they're unsure about you, they won't go into small places willingly unless it's their lair/den/nest, and, if they're completely familiar with you, they're very good for cuddling.

^.^ Sorry about the chat-speak, but I thought it was kind of fitting.

What is good instead of a maze would be some different length tunnels. Pigs love tunnels.