yo-yo 
(yōyō′)
(yōyō′)n. pl. yo-yos
1. A toy consisting of a flattened spool wound with string that is spun down from and reeled up to the hand by motions of the wrist.
2. Informal One that undergoes frequent abrupt shifts or reversals, as of opinion or emotion; a vacillator.
3. Slang A stupid or objectionable person.
intr.v. yo-yoed, yo-yo·ing, yo-yos
Informal
Informal
To undergo frequent abrupt shifts or reversals, as of opinion or emotion; vacillate.
[Originally a trademark.]