This is a simple, harmless, and hilarious practical joke,

This is a simple, harmless, and hilarious practical joke, that has claimed me
as a victim. The setting is a pool hall, bar, or anyplace else with a pool
(billiards) table. Place any ball at one end of the table and give your victim
the cue ball. Challenge the victim to focus on the cue ball while walking
around the pool table three times. At the end of the third time, the victim
is to place the cue ball on the table, take a cue stick and hit the cue ball so
that it stikes the ball at the other end of the table. This is very difficult
to do; not because of a loss of coordination from walking and staring at the
ball, but because while the victim is concentrating on the ball, you lick your
finger and wipe chalk off the end of the cue stick. The victim will miscue
almost every time. It gets funnier, because if the victim is like me, he/she
will be determined and try it again.