The "Best Evidence Topic" reports from the Manchester Royal Infirmary are published in the Journal of Emergency Medicine. Overall, they are meant to summarize evidence regarding more practical, clinical applications. One of the recent summaries focuses on appendicitis, and whether eliciting pain during coughing, percussion, or hopping is useful in ruling in or out disease.
For this topic, they summarize a few articles - mostly following a prospective derivation study in which hopping/percussion/coughing was 93% sensitive and 100% specific for appendicitis. Unfortunately, the test performance didn't quite hold up - sensitivity ranging from 72% to 89%, depending on age group, and highly variable specificities.
So, unfortunately, somewhat like the "hamburger test," you won't be able to base the entirety of your clinical disposition on this, but it's not an irrelevant input into your general clinical gestalt.
"BET 1: Is abdominal pain when asked to hop suggestive of appendicitis in children?"