It's a emoticon thingy that means you are thankful and full of joy for whatever reason.
Person 1: "I got you a gift card"
Person 2: "Thank you <:D"
Ortho-goddess in the making and a Tik Tok prodigy
"Oh wow, this videos is made by such a D "
D- Dino nuggies. Best snack in the world.
John: Did you give her the D?
Tim: of course I did...everyone loves Dino nuggies.
uh... why you searched for that? its just leter D!!!!!!!!!!!!!!!!!!!!!!
Whats your name? It starts with D, right? Is it Dumb Stupid Bitch?