be a no-no(redirected from is a no-no)
be a no-no
To be objectionable or prohibited, as of an action. If you're trying to become friends with this woman, criticizing her style of parenting is a no-no. Talking in the middle of a Broadway play is a real no-no.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.