Appear suddenly or unexpectedly. For example, I didn't know anyone in the group until Harry bobbed up. This term uses the verb bob in the sense of “to bounce,” a usage dating from Chaucer's day. [Late 1800s]
The American Heritage® Idioms Dictionary Copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
How to use bob up in a sentence
If they see us splitting the breeze down Lost River, they won't look for us to bob up from the opposite quarter to-morrow.Raw Gold | Bertrand W. Sinclair
His raft began to bob up and down, and pretty soon a wave washed over it and wet Bumper's feet.Bumper, The White Rabbit | George Ethelbert Walsh
All would rise on their hind-feet and bob up and down, at the same time giving the peculiar cry.Red Hunters And the Animal People | Charles A. Eastman
"And every time I look at the picture of the fire it'll bob up before me and make me shudder," remarked Will.The Outdoor Chums After Big Game | Captain Quincy Allen
Aunt Gwen is a character to be watched, and bound to bob up serenely, with the most amazing assurance, at unexpected times.Miss Caprice | St. George Rathborne