A real life example of a cliff are the white cliffs of Dover.
There are actually quite a few real life examples of a midpoint. The Equator is an example of a midpoint.
A mirror image of something
Any pythagorean triangle with unequal legs.
The PYRAMIDS at Giza in Egypt. Hence the name 'pyramid'.
A real life example is a Toblerone chocolate bar which is in the shape of a triangular prism.
A building would be a perfect example. If you simplify the details of a building, it becomes a rectangular prism. If you specifically mean a "square" prism, that would be a cube, an example of which would be a Rubik's Cube or a few dice.
A solid brick is a rectangular prism. (this one example of many)
stuff
A pencil.
A tent
An Amicelli box! THIS IS NOT TRUE IT IS HEXAGONAL!!
The Pentagon Department of defense office building
Pup tent or lean-to
t.v screenpicture frame
An excellent real life example of a square pyramid are the Pyramids at Giza. They have four sides at the base and come to a point.
A square pyramid is a polygon that has a square base and four triangular sides. A real life example is the Great Pyramid of Giza in Egypt.