1. To avoid becoming excited at the prospect of something good happening in the future. I hope Sadie hasn't gotten her hopes up about going to the carnival tonight, because I don't know that we can go. Don't get your hopes up about seeing Aunt Jen this weekend—I hear she's having car trouble.

2. To avoid causing one to become excited about or expectant of something good happening in the future. Please don't get the kids' hopes up about Disney Land—we still don't know if we can afford it. I don't want to get your hopes up or anything, but there's a chance we might be hiring for a position in your field of expertise.