* Songs that *feature* a pig-like character? This could include songs about mythical creatures, animals, or even metaphorical representations of certain personalities.
* Songs that evoke the *themes* of the Pigman novel? This would encompass themes like loneliness, friendship, rebellion, growing up, and confronting authority.
* Songs that *specifically* relate to the character of Mr. Pignati, the Pigman himself? This would look for songs about kindness, loneliness, and possibly even a bit of the sadness and darkness in Mr. Pignati's past.
To give you a more helpful response, please clarify what you mean by "relate" to the Pigman. Are you looking for songs about a specific aspect of the story, or just general songs that have a similar vibe?
Once you tell me what you're looking for, I can suggest some songs that might fit the bill.