Accident, Defiance, Experimentation or Stupidity

I know it wasn't an accident. Take that one off the list right off the bat. I was making grilled cheese sandwiches at the stove for our lunch. Maddie asked for a drink of water and went to the table with it. She climbed up on her chair and took a sip. Then she seemed enthralled with looking in the cup. She stood up and held it to her face for a while. Then she held her arm out away from her, over the table and dumped the entire cup on the table. WHAT WAS SHE THINKING???? I've had it. I am so glad Jacob was sleeping (despite their most valiant efforts to ruin his naps and waking him three times in four hours, totally destroying my morning and wasting my time trying to resettle him over and over). Since he was down, I was free to deal with the situation in a level headed manner. I asked her why she dumped the water. "Because I like to dump water," came the reply. I gave her a rag and made her clean it up as best she could. Then I helped get the rest and sent her to time out, a place she spends about half her day. She's already been in time out multiple times today and it's only noon. It just doesn't phase her. Time out is worthless with this child. She goes willingly. Happily actually. Then she waits until I come to talk and release her. She gives me a hug and smiles as she says sorry and toddles off to wreak havoc again. I know with Ben there was a period of about six months maybe that it felt he was in time out all the time too. It's just that it made a difference and had an effect on him. He hated to be removed from the action or taken away from his toys. It was a punishment to him. Maddie seems to think with simply interupt one fun game with another funny game called "Time Out" where she gets to wiggle her legs on the stairs and give mom a hug before we return to our original fun games. What do you do with a kid who doesn't mind time out? It doesn't accomplish it's purpose if it doesn't feel like a punishment to them.