How could I say no? We got our coats, and headed down to the park. We climbed the play structure, ran along the low concrete wall, walked in the woods looking for pretend crocodiles, and sang the Squid Song through the speaking tube. And we slid down the slide (but many more times than just once).
When it was time to go home, we had to slide down the slide just a few more times, but we headed off without any fuss to speak of.
It was fun being Uncle Evan.