You keep using that phrase…I do not think it means what you think it means.

If you don’t know where the above quote comes from, please be sure to watch this. 

Simeon has learned a new phrase:  “I’m serious!” 

I’m not exactly sure where he picked up this phrase, but he doesn’t use it appropriately.  I told him it was time for a bath.  He got a huge grin, then started running ecstatically for the bathroom, yelling, “I’m serious!  I’m serious!”

I believe the word you’re looking for is “excited.”