For me it's the Laughing Place song. My DH was on some heavy pain killers the first time we went together, and for the first two days he was a little out of it. He got the words all wrong. He kept singing, "laughing room, laugh, laugh, laugh" with this big, goofy smile on his face. Whenever I hear that song, it makes me think of that first trip together, and gets me excited for the next one coming up.