Those of you who smack, what do you deem smack-worthy?

[NMS1]

My daughter is approaching 4 and I find that the threat of a smack usually brings her into line. My husband comes from a family that used the cane (as well as a school that caned its pupils) and did suggest us caning her for serious offences but I personally find that too humiliating. A quick slap across the legs when she is having an out-of-control tantrum because she isn't getting her way or is just totally ignorning me works wonders. Sometimes a "time-out" works better - it just depends on her mood and what she has done.

I do not smack her in public as I also feel that is demeaning for her but I will pull her aside from her friends and scold her when necessary.

[no two kids are alike]

As a toddler I could take my little boy to anyone's house and he was well behaved. If he tried to touch something like the video or music centre, all I had to say was a firm "no'and he would come running to me saying sorry and not do it again. Time out was the worst punishment for him. My daughter at that age was the opposite. She would challenge you with a look that said'just try me". You could explain until you were blue in the face. Time out didn't matter because she liked going to her room.Once she knew she wasn't supposed to do something she would try to do it again and again. The only thing that stopped her was a quick smack on her hand. Although I never had to smack her once she was past the toddler stage, she still has a very stubborn streak in her and test the boundaries all the time.
I totally dissaprove of smacking in anger but have resorted to it sparingly as mentioned to discipline ( and sometimes that hurt me nore than her!).