A pastor was teaching on Psalm 76, noting that when Jesus was transfigured the disciples fell on their feet. This is a conflation of “fall on (one’s) knees” (to kneel down as a show of respect) and “be swept off (one’s) feet” (to become very enamored with someone). Both expressions involve admiration or awe of another. Also the body parts “knees” and “feet” seem to be the source of the confusion here. Of course, “fall on (one’s) feet” is an expression indicating one who is lucky or successful, and I suppose that is true in the disciples’ case. However, I believe it is a malaphor given the context. A big thanks to Steve Grieme who heard this one and passed it on!