When you open up the Korok Forest by navigating through the Lost Woods, you’ll meet a bunch of koroks who have quests for you to complete — The Korok Trials. A few of them are tied to shrines — Trial of Second Sight, The Lost Pilgramage and The Test of Wood — but one is another slideshow.
A korok named Peeks is walking around down by the entrance to the village. He’ll tell you that he wants more than anything to see a blupee, even if it’s just a picture.
Where to find a blupee
You’ve probably seen a blupee already, even if you didn’t know what it was. They’re very skittish and run away before you can get close. Blupees almost always (but not always) appear in the woods, usually (but not always) at night.
The best place to find them is north of Kakariko Village, in the woods between the Great Fairy fountain and Ta'loh Naeg shrine. You might run into them other places, but it’s more common to run into them here.
Getting Peeks’ picture
Blupees will run away if they even get a whiff of you, so it’s basically impossible to get close to them. To get the picture that Peeks wants, you’ll have to be careful. Drink a stealth elixir, wear the stealth set and crouch. When you are lucky enough to find one, activate your camera and zoom in as much as you need to to get the shot.
Head back to Korok Forest and show off your picture to Peeks, and he’ll give you a silver rupee.
Another way to shoot blupees
After you’ve taken a picture, make sure to shoot the rupee with your bow. It doesn’t kill the blupee, but it will drop a pile of rupees.