Jumping Jehoshaphat:

Today is the feast day of St. Josaphat. I set out today to find the origin of the term “Jumping Josaphat.”

Jumping Jehoshaphat: Jehosaphat was a wealthy king of Jerusalem. One day an army from the east march on Jerusalem to take his gold. Jehosaphat told the people not to worry that the battle would be his and Judas’s on the following day. The people let out a joyous cry “Great Jumping Jehosaphat”. I am not sure exactly the meaning of the saying other than total joy at not having to go to war!!

Reference: http://www.rootsweb.ancestry.com/~genepool/meanings.htm