When a person's body flips over in such a way that the heels (of the feet) coming flying up over the head, we say that they have gone "head over heels". Example: "He was running so fast that when he jumped and got hit he went head over heels." When a person falls in love, it can also make a them feel dizzy (in the "head") and out of control. Example: "I've never seen him like this before!" Answer: "Yes, he's completely head over heels about her." You fall "head over heels in love" with someone when you think about that person all of the time and feel almost dizzy when they are around. Example: "I have been head over heels about my girlfriend since the day I met her."