Pistons can push players up onto a ledge

The bug

Have a full block with a glass pane or iron fence on top of it, place a piston facing the glass pane/ iron fence with a 1 block space in between them, then stand in that 1 block space with the piston at face level and power it; Sometimes you will teleport on top of the solid block, but most of the time you should teleport on top of the glass pane / iron bars.