squib 
/ˈskwɪb/ noun
plural squibs /ˈskwɪb/ noun [count] : a small firecracker
damp squib
Brit : something that is disappointing because it is not as exciting or effective as expected
▪ The stock turned out to be something of a damp squib.
▪ The stock turned out to be something of a damp squib.
