Is it ensure, insure, or assure?
To have complete control over a person; have a painful advantage: We've got them where the hair is short, and they can't squirm out ( first form 1872+, second 1888+)
To have someone in a painful and helpless situation; have absolute control over; HAVE someone BY THE BALLS: When life gets you by the short hairs, it doesn't let go/ Someone nasty and ruthless has him by the short hairs/ You're in no position to make deals. We got you by the curlies/ We've got him by the knickers and he's hurting
[1891+; fr the short hairs growing on the scrotum]