J F'n C
A big, loud, and very rude way to show you're shocked. Use it in church if you're ready to be thrown out for being too loud.
He said "J F'n C!" when the pastor started juggling holy water and fire.
She screamed "J F'n C!" when the church bells started ringing and the ceiling rained down.
He yelled "J F'n C!" when the priest turned into a giant dragon and started preaching.