From Wiktionary, the free dictionary
Literally, “am I Jesus?”
bin ich Jesus?
- (idiomatic, potentially somewhat offensive) Said in response when asked something one could not be expected to know or be able to do.
Meinst du, sie hat den Brief schon gelesen? – Woher soll ich das wissen? Bin ich Jesus?- Do you think she’s read the letter yet? – How would I know? Am I Jesus?