This one was told to me by an instructor whilst I was learning to fly in the early 90's in Africa.....
This particular training/GA airport could get a bit busy in the circuit but had a number of fairly competent controllers who could get a little excited when things were not going exactly as they should. On the day in question there were six or seven aircraft in the circuit when an inbound out of town aircraft starts making calls requesting directions to the airfield due to the haze that builds in summer and if you don't know where it is the field is difficult to see until you are right over it even with good weather. The controller gives directions and help as best she can but the inbound pilot can't see the field and has descended to what is circuit height in an attempt to see the field. Poor old controller can suddenly see the arrival which is now about to enter her well organised circuit overhead the field and issues the following instruction....
"All stations .... this is ....Tower, please scatter!"