It can be fun researching all the strange games golfers like to play.  Here's one which fits into that category, "Hit It Long."

In Hit It Long an imaginary line is drawn at the flagstick, perpendicular to the line from the tee.  If at any point in time a player's ball crosses the plane of that line, that player loses the hole or a betting unit.

The format of the game can be a dot format (say $1.00 per dot), skins game, match play, stroke play or other formats.

Variation

A variation of the game could be just the opposite.  At some point in time the player's ball must travel past the flag.