Three friends walk into a bar, sit down, and when waiter comes to them, they ask him how much is the beer. The waiter tells them that the beer is $10$ dollars. They order three beers and each of them gives him $10$ dollars.
A few moments later the boss of the bar arrives and asks waiter how much money did he ask from the three guests which ordered three beers. The waiter said to boss that he asked for $30$ dollars from them for three beers. The boss then said to the waiter that he give them back $5$ dollars because the boss knows those three friends and does not want that they pay the full price.
When waiter was walking towards those three friends he said to himself that he will not give them back $5$ dollars but will instead take $2$ dollars for himself and return $3$ dollars to them, $1$ dollar to each of them.
And so, when waiter came to those three friends he told that the boss said that he wants that the beer for them has the price of $9$ dollars and returned to them $3$ dollars, $1$ dollar to each of them.
So we have this situation, after the waiter returned $3$ dollars to three friends each of them gave for the beer $10-1=9$ dollars. That means that three of them together gave $27$ dollars, and if we add to $27$ the $2$ dollars which waiter took for himself we arrive at $29$ dollars in total.
The question is:
Where is $1$ dollar lost?
It makes no sense to add 2 to 27. The cash that the boss receives is 27-2=25.