Not a crank call, but funny as hell nonetheless. I was aboard a Frigate when I was in the Navy (FFG-34), and we were doing drug interdiction ops off the coast of Haiti sometime in '96. Well, we got information particular vessel was a notorious smuggling boat and was headed to the states, so we chased them back to Port-au-Prince. But they beat us into Haiti's territorial waters, so we had to let them go. We were then assigned to patrol the area, in case the boat tried to sneak by in the middle of the night.
After a week of nothing happening the CO was getting impatient and devised a plan... a coastie ship a few miles away would send a distress call over the unsecure shipping frequency, and we would pretend to leave to rescue them. Of course we were just giving the smugglers a chance to bolt from Haiti and would be waiting for them when they did.
Two nights later the distress call went out and we tore off at 30 knots for a while.. then we went and hid around a large land mass off the island that offered us visual and radar cover from the vessel, should try to leave.
We all waited in the CIC as silently as in those submarine movies, listening to the shipping traffic radio for some sign that the boat was getting underway. After about an hour of utter stillness, a crackling voice came out of the radio and, very slowly, said "US Navy warship... we know you're out there...!"
Boy was the CO pissed! Most of us little people were laughing to tears, but had to stifle it, since the OPs officer shot us a dirty look.