For this trick you need to know what a overhand shuffle is. You should also know that you can maneuver the top card to the bottom easily. And the bottom card to the top.

Therefore, it may appear that you have mixed the cards after performing the overhand shuffle twice, when actually you still have [...]

This deck is a trick deck wherein the backs of the cards used have a thick, non-slick surface. The cards are placed back to back in certain pairs. There a few rules in determining these pairs:
1) Each pair adds up to 13 (9 and 4; 6 and 7; queen and ace; king and king; [...]

Effect
A person becomes seemingly weightless and may be lifted from a chair on the index fingers of four smaller people. Although various explanations have been proposed, this classic stunt continues to mystify and amuse.
Stage 1

The person to be lifted (choose a fairly heavy person) should sit relaxed but upright [...]