Sometimes this particular day of Holy Week is called "Spy Wednesday." Wednesday is the day tradition has picked to highlight the bad guys plotting to kill Jesus. Jesus' enemies were looking for a way to trap Jesus and kill him. Jesus was attracting followers (think of the parade with people celebrating with palms, His arrival in Jerusalem). So when the apostle, Judas Iscariot came to them with a plan to turn Jesus over to them, they knew they could be rid of Jesus.
Since Judas and Jesus' enemies were watching Him and plotting against Him, the day is called Spy Wednesday.
