jump the track
Suddenly switch from one thought or activity to another. For example, Joe was describing his trip to Australia and, jumping the track, began complaining about the airline, or They couldn't decide on the next step and now the whole reorganization plan has jumped the track. This expression alludes to a train going off the rails. [Colloquial; early 1900s]
Words nearby jump the track
jump shooter,
jump shot,
jump spark,
jump suit,
jump the gun,
jump the track,
jump through hoops,
jump to a conclusion,
jump turn,
jump wire,
jump-off