Kids will get into stuff no matter how much you have kidproofed your house. I stayed home with the kids today, and my daughter was trying to get into everything.
To try to express the importance of not doing such things, I raised my voice--not in an evil-sounding way.
Now keep in mind that she's 10 months old, so she's not much of a conversationalist.
After I picked her up and moved her into the living room, I told her that I didn't want her to get into that stuff because she could get hurt.
She looked at me, smiled widely and gave me a big kiss.
And then went right back where I told her not to go.