Damp Squib Meaning

(idiomatic, by extension) Anything that doesn’t work properly, or fails to come up to expectations.

Example: A firework that fails to go off, due to wetting.
2012 December 29, Paul Doyle, “Arsenal's Theo Walcott hits hat-trick in thrilling victory over Newcastle”[1], The Guardian:
  Arsène Wenger confessed: "The result was not an accurate indication of the match." Certainly, at half-time it seemed unlikely that Arsenal would catch fire so spectacularly because the first half was a damp squib of a display from Wenger's team, as Newcastle initially showed no ill-effects from their Old Trafford ordeal.