Go Cold Turkey



Example:
Frank: I’m thinking about quitting fast food.
Aaron: That’s really good.  It’s really unhealthy to eat fried food every day. 
Frank: Yeah, I’m going cold turkey.  No transition period.
Aaron: Wow!  That’s difficult.  I usually cut some foods slowly.  I can’t give up food I like all at once. 

Meaning: Go cold turkey is an expression used when someone stops doing something without a transition period.  It’s a very sudden stop to an action or habit.