I can tell you that people often experience unexpected and surprising conversations in their lives. It's not uncommon for someone to say something hot (in the sense of being spicy or exciting) or surprising, whether it's a joke, a compliment, a confession, or an unconventional opinion.
Individual experiences can vary widely, so the hottest, least expected thing someone has said to you would depend on your own personal interactions and circumstances. People often share memorable experiences of receiving compliments or hearing unexpected confessions or declarations of love, which can leave a lasting impression. However, the specific content of such encounters is unique to each individual.