It's a nicer way of saying ''I don't care''
Example 1 :
Sasha : I Have This New Amazzingg Boyfriend
Emily: Nice To Know.

Example 2:

Elli: Today Is A Great Day For Me, I'm Having The Best Luck I've Ever Had
Brandy: Nice To Know.

Example 3 & Last One :

Jordan: I Love Her SOO Much.
Caitlyn: Nice To Know. I Wish You Guys The Best.
by Kayla Crowder August 20, 2013
Get the Nice to know mug.
An expression said to someone who is about to do something which will put him/her at great risk.
Mark: "Hey man, did you sell your plasma screen TV yet?"
Johnny: "Yeah, I've got a guy who wants to buy it. I'm meeting him on a corner in East Oakland tomorrow night at 1am."
Mark: "Good luck with that. Nice knowing you."
by Nicholas D January 14, 2012
Get the nice knowing you mug.