show (one's) horns(redirected from show her horns)
show (one's) horns
To reveal one's evil or malicious nature. The devil is typically depicted with horns. I thought I could trust Eric until he showed his horns by spreading rumors about me. Jill definitely sabotaged my last two relationships. She might seem nice, but she always shows her horns eventually.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.