see lots of people put this on their profile, want to know where the phrase comes from ??
This phrase probably alludes to signaling the start of a race or other contest by dropping a hat. [Late 1800s] commonly used to start a race or a fight
copied from google:
Immediately, without delay, as in We were ready to pack our bags and go on vacation at the drop of a hat. This phrase probably alludes to signaling the start of a race or other contest by dropping a hat. [Late 1800s]