* To be surprised, astonished, or amazed.
* To be annoyed or irritated.
It's a rather informal and somewhat old-fashioned expression.
Example:
* "Be jiggered! I can't believe I won the lottery!" (Surprise)
* "Be jiggered! I left my keys in the car." (Annoyance)
It's similar in meaning to expressions like "Crikey!", "Goodness me!", "Blast!", or "Blimey!"