Cardiff Crown Court was told Mohammed Ghamghami's joke about Iranian jewel thieves upset Tajmry Mehdy, 33, who is alleged to have attacked him.
The incident took place at Tredegarville Baptist Church in Cardiff where Mr Ghamghami was thought to be covered in blood and suffered a broken nose and cheekbone.
Mr Mendy, now living in Manchester, denies actual bodily harm.
The trial continues.
