"Trigger finger" is a phrase used to describe a condition where one of your fingers gets stuck in a bent position and then suddenly straightens with a snap, similar to pulling a trigger. Full definition
I hope you have your online shopping trigger fingers ready, because this is a deal you CAN NOT pass up. (theheartsdlite.com)
Combined with the shooting this makes for some epic battles where skillful driving is just as important as a quick trigger finger. (wolfsgamingblog.com)
In the campaign mode, players must balance strategic prowess and resources while maintaining a steady trigger finger throughout 15 maps. (shortpause.com)