An alert passenger on bus # 143 from Kochav Yaakov to Jerusalem spotted a religious looking woman in large sunglasses holding a open book of assorted Psalms - upside down. She made sure the 'reader' wasn't just dozing; she was actually scanning the bus under the shades.
The driver was informed, and the IDF boarded the bus, apprehending in fact two such impersonators, lacking proper ID.