Meaning
A grayish-white human skull with dark eye sockets and a row of teeth. Its traditional meanings are death, danger and spooky themes, which still apply around Halloween or in horror talk.
In casual chat, though, it most often means “I’m dead,” as in laughing so hard you figuratively died: “He tried to parallel park for twenty minutes and gave up 💀” Older readers may take it literally and think something grim happened, so with parents or in serious contexts, a laughing face is the clearer choice. It can also mean being dead tired or mortified.