In Markus Zusak's novel The Book Thief, after much teasing earlier in the story and swearing she would never kiss him, Liesel does indeed get up the courage to try and kiss her best friend Rudy. The scene is found in the section titled "The Anarchist's Suit Collection" of Part Eight, approximately on page 311.
On Christmas Eve of 1942, she marches next door, saying to herself, "To hell with being out too late." She then tells Rudy she has a Christmas present for him and asks him to take her to her father's abandoned tailor's shop. She then has him dress up in a blue suit from the shop. Liesel teases him by saying he looks "Not bad" and that "[his] shoes let [him] down. And [his] face." When Rudy stalks towards her, pretending to be angry, because the electricity has been shut off in the store and they are struggling in the dark with just a lantern, Rudy trips and falls. Death, the narrator, then describes Rudy as closing his eyes in expectation of Liesel's kiss and Liesel as rushing over and crouching above Rudy, as Death thinks to himself, "Kiss him, Liesel, kiss him." But, instead, she asks if he is alright, and Rudy's response is to say, "I miss him," referring to his father, Alex Steiner, who was viewed as an anarchist by the Nazi party for refusing to persecute Jews and sent to work at an army hospital just outside of Vienna.
Liesel ends the scene by wishing him merry Christmas, helping him to his feet, and not kissing him.