When one of my friends showed me a picture, I was amazed on how it was done. The picture shows two people standing on the ground, but one of the people appears to be much taller and bigger than a normal human being. How was this picture taken?
I think the technique you are referring to is Forced Perspective
There is a guide here on how to achieve some interesting shots
The bottom line is you need to have physical distance between subject one and subject two - this technique success depends on loads of factors - e.g. if its done with the right subjects and right setup - It has to look unforced.
I like the Eiffel tower example in the guide but the hand shake one would have been good if the distant subject was well lit.
As a further note on cam settings - your going to want a small aperture (higher than f/8) to capture sufficient detail in the foreground and background
Plan your shot!