The concept of Pechaflickr is based on the Pecha Kucha presentation style that utilizes 20 seconds to present each of 20 slides. http://pechaflickr.net/ generates random images from a keyword search of flickr.com. Your students create a story from the images. The storyteller(s) do not know what images come up.
While Pechaflickr pulls images tagged as "safe" from Flickr, inappropriate images may slip through. There is not a 100% effective way to prevent a questionable image from popping up.
You can set up your own version of this using Google Slides with images you choose ahead of time. By publishing your slide deck and setting an “autoadvance slides” time, you can achieve the same type of storytelling tool. Below is a link to a template with directions.
Below is a link to a template with directions.