spring on someone

spring on

1. To leap, pounce, or dart onto someone or something. The dogs sprang on the sofa as soon as they were inside the house. I love watching the kids spring on Sarah when she comes home from work.
2. To tell, present, or disclose something to someone that they were not expecting. In this usage, a noun or pronoun is used between "spring" and "on." I'm springing a trip to Barcelona on my wife for her birthday. The boss sprang several huge changes to the project on me at the last minute.
See also: on, spring

spring on someone

Present or make known unexpectedly, as in They sprung the news of their engagement on the family last night. This idiom uses spring in the sense of "make a sudden move." Mark Twain used it in Tom Sawyer (1876): "Old Mr. Jones is going to try to spring something on the people here tonight."
See also: on, someone, spring