I was a district leader when the U.S. invaded Iraq. On April Fools we had a district meeting where I pretended to get an emergency page from the Mission President. I went out of the room for a few minutes, came back, and told my district that Saddam Hussein had given the U.S. 24 hours to leave the country, or else he would attack using nuclear weapons. I told them the mission president told us to return to our apartments and begin a fast.
One of the missionaries started bawling and said we needed to have a kneeling prayer before we left. I asked him to say the prayer. It was really hard to not laugh.
The missionaries got to their cars/bikes, where I had put "April Fools" signs.