The title—Lips Touch: Three Times—refers to the three kisses that happen within the book, one in each of the three short stories. Right away, we know we're in for some lip locking, and we know that these smooches are probably going to matter big time. Otherwise they wouldn't be referenced in the title.
In "Goblin Fruit," the kiss occurs at the end of the story when Kizzy willingly kisses Jack Husk even though she suspects that he's a goblin, thereby giving up her soul. Anamique in "Spicy Little Curses Such As These" breaks her promise to never speak when James kisses her—and she ends up killing everyone in the near vicinity as a result. And in "Hatchling," Esmé's journey into Tajbel is launched when she wakes up with one blue eye and the memory of a mysterious kiss that she never directly experienced.
Clearly kisses are no joke in this book and lead to some serious consequences—which is why they get to figure prominently in the title. For more on this, swing by the "Symbols" section.