slip up on

slip up on (someone, something, or an animal)

to sneak up on someone, something, or an animal quietly. I slipped up on Harry and scared him to death. The cat slipped up on a mouse and grabbed it.
See also: on, slip, up

slip up on something

to make an error in something. I guess I slipped up on that last job. Fred slipped upon compiling that listthere are a lot of names missing.
See also: on, slip, up