If you jerk something or someone in a particular direction , or they jerk in a particular direction, they move a short distance very suddenly and quickly.
physical jerks
to move or cause to move with an irregular or spasmodic motion
jerk off
To jerk off means to → masturbate .
knee jerk
If you call someone's response to a question or situation a knee-jerk reaction , you mean that they react in a very predictable way, without thinking .
soda jerk
a person who serves at a soda fountain
soda jerker
a person who serves at a soda fountain
jerk around
If you say that someone is jerking you around , you mean that they are not being honest with you about something.
clean-and-jerk
a lift in weightlifting in which the weight is held momentarily at shoulder height before being thrust overhead