The part of a suitcase that is designed to get snarled up on conveyor belts in airports. Some of the more modern adlestrop designs have a 'quick release' feature that enables the case to flip open at this point and fling your underclothes into the conveyor belt's gearing mechanism.
See Adlestrop, Aird of Sleat, Glentaggart, Hever.
source : The Meaning of Liff