The screening of baggage for explosives is sadly a necessity in the modern jet travel age, and the technology applied to the detection of bombs in luggage is (at least in some airports) amazing. One machine was capable of 'sniffing' nitrogen concentrations so minute that a rolled-up plastic belt could set it off.
Another component of explosive material can be glycerine, which leads us to an event during crew boarding of a flight recently. The crew whizzed through the scans as normal, they all know what they shouldn't pack and don't expect to set off any alarms, however one flight attendant's bag set off the sensors.
She was kept behind for 20 minutes while her baggage was thoroughly searched. She was finally allowed to board once the offending item had been identified and determined not to be a risk. A glycerine based suppository was the culprit, and the red faced lady had to endure being referred to as 'The Blonde Bombshell' for the rest of the flight.