It's my dog Cassie's first spring in New York, and she's really enjoying the long, soft grass in Central Park (which her yard in Los Angeles didn't have) and the supremely doggy act of a luxurious roll in it, like this.
As I understand it, dogs love this activity because the soft surface feels great on their skin and the rolling motion produces exquisite sensations. It's also cause for ecstasy because it smells delicious (which is why they dive their faces in first), most likely because something died in it. Nonetheless, it's usually harmless, and almost always irresistible.
I was trying to think of an analogous human experience (without which no animal anecdote is complete), and realized that it's exactly like being in a bed you've been in before.
(Post title from the sunny-day instrumental by the great Hugh Masekela.)