Table-top football can played with a paper 'football' on virtually any size or shape table. This is a two-player game. It requires a minimum of intelligence and skill. The game is generally played by elementary and junior high school students, though you may find it being played in high schools and amongst very bored adults.

Find a table and an opponent:

Take a 8.5 " by 11 " sheet of paper and using your origami skills fold it into an isosceles triangle with a base approximately 3 " and an altitude of approximately 1.5 ". If you're good, you'll be able to do this using the entire sheet of paper and you won't need tape to hold it together.

The Play:

Sitting at opposite sides of the table (if it's a round table, you'll have to figure something out on your own), Player A begins by sliding the footbal towards Player B. Player B lets the football come to a rest and slides it back towards Player A. Play continues until one player scores a touchdown or the football leaves the table.

When the football is slid off the table:
If Player A slides the football and it goes over the edge of the table and falls off, then Player B gets to attempt a Field Goal. Field goals are attempted by using one hand to stand the football on the table (one of the football's corners or sides) and trying to 'kick' it between the uprights (goalposts) using a finger of the other hand..

The player who is not kicking the field goal creates uprights by holding his hands in front of himself with palms facing away and thumbs out at right angles. Then placing the tips of his thumbs together creating three sides of a rectangle - the top being open. A successful field goal scores 3 points.

Scoring a touchdown:
A touchdown is scored when any part of the football is hanging over the edge of the table. The player who slid the football scores 6 points and gets to attempt an extra point or PAT (point after touchdown). Extra points are attempted the same as field goals, but they only count for 1 point..

Ending a game:
Games can be played to a certain point level, for a given length of time, or until the players decide enough is enough. This should generally be agreed upon beforehand. The player with the most points wins.
Variations:
Basically, changing the size and/or shape of the football -- or changing the size and/or shape of the table.