These symbols highlight socially undesirable behavior in more accepting forms.

The most straightforward definition I've come across is 'unusual or undesirable behaviour'.

Peer pressure remains the most effective means of curbing this undesirable behavior.

You will, at times, have to make the consequences of undesirable behaviour costly for the child.

This does not mean, however, that parents should be overly permissive and let children get away with destructive or undesirable behavior.

Restraint is used, after a warning, to bring about the end of undesirable behaviour.

He was restrained from completing the undesirable behaviour of getting into their bed.

If the undesirable behavior persists, parents should consider suggesting that their children find other friends.

Look for alternative ways of responding to undesirable behavior.

When the system enters this problem state, unexpected and undesirable behavior may result.