A strong case for the button fly.
Between 2002 and 2010, an estimated 17 616 patients presented to US EDs with trouser zip injuries to the genitals. The penis was almost always the only genital organ involved. Zip injuries represented nearly one-fifth of all penile injuries. Amongst adults, zips were the most frequent cause of penile injuries. Annual zip-related genital injury incidence remained stable over the study period.