How...?

Jilly has gotten really good at stall tactics when it comes to bedtime. Recently, she has been getting out of bed and playing. Well, to combat this, when she jumps out of bed one of us goes up, tucks her back in, and gives her a warning "If I have to come back up here, your baby doll is coming downstairs with me.". So far, it has worked. Then there was tonight. She must have heard me hitting the top of the stairs, and she went jumping back into bed. This made me laugh even before I went in, but what made it worse was the fact that Jilly was in the middle of pulling the covers over her head, in an attempt to fool me into thinking she was sleeping. So now I'm in stitches, and trying to tell her it's time for bed, and I want her to take me seriously, but there's no chance of that cause I'm laughing way too hard. So I finally get myself under control, and tell Jilly "It's not play time, it's sleepy time. Close your eyes, and go to sleep." To which she replies "I don't know how to close my eyes, Mommy. Show me." Had this been any other night, I would have just told her that she knows how, now go sleep...but since I was already giddy and giggly, it got drawn out into a 5 minute laughing jag by both of us. Needless to say, she has been asleep for a few hours now, not another peep after "learning" how to close her eyes again!