What does it mean when a girl replies "Idc" when you text her about your day?

We attend the same high school. Something very hilarious happened in my class today, and I thought she might enjoy hearing about it. I text her about it, with a laughing emoji at the end. After an hour, she texted back, "Idc (with the laughing emoji)." What does that mean? She put a laughing emoji, just like I did, so did she find it funny? If so why did she say "idc" before putting it? Idc means "I don't care" in case you didn't know. But why the laughing emoji then?
What does it mean when a girl replies "Idc" when you text her about your day?
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