From Longman Dictionary of Contemporary Englishdamp squibdamp squibDISAPPOINTED British English informal something that is intended to be exciting, effective etc, but which is disappointing → damp
Examples from the Corpus
damp squib• The fireworks display that heralded the opening of Antwerp 93 went off like a damp squib.• The traditional Easter turkey boom - the second biggest after Christmas - was a damp squib because hard-up families bought cheaper chickens. 