When sending a quick double-pulse to a sticky piston facing up having a solid block on top with a falling block (sand/gravel) on top of it, the sand/gravel will get pulled through the solid block and switch places. Demonstration of this can be seen here: https://www.youtube.com/watch?v=KLEA3sVaj4o
Duplicate of MC-4789, please use the search function to see if your bug has already been submitted. Currently over 49% of tickets are being closed as duplicate.