From Longman Dictionary of Contemporary Englishbe caught nappingbe caught nappinginformalREADY to not be ready to deal with something when it happens, although you should be ready for it The German team were caught napping and Lampard scored the winning goal. → nap
Examples from the Corpus
be caught napping• I was reminding the golfing spirits that I could not be caught napping.• Quakers were caught napping again two minutes later.• Nowadays, no company can afford to be caught napping by a technological development.• Stock traders who ignore these signs are in danger of being caught napping when a recession hits. 