It happened to a friend (with a pilot license I precise).

He was flying a small two seat aircraft and got contacted through the radio and for asked if he was ok to do a exercice with military aircraft.

He agreed so soon after two fighter jet arrived on his left and right. To be able to fly at the same speed as him they were almost standing vertically. They directed him for a bit without any radio contact, then thanked him through the radio and left.

They were doing a exercise to direct someone with no radio contact.