A sharp pinch or jerk; a twist or twitch.
"The sudden tweak in his shoulder made him drop the heavy box right on his foot."
pinch or squeeze sharply
"He winced as I tweaked his arm to get his attention before we left the house."
To pinch and pull with a sudden jerk and twist; to twitch.
"The cat gave my leg an unexpected tweak that nearly made me jump out of my chair."