I prefer jelquing from the standpoint of safety..that said, several worshippers have pumped my cock a few times and the result was an insanely thick cock... went from 7.5 normal girth to much thicker and the soft foreskin puffed up like an humongous bulbous donut shape when out of the pumping tube...length maxed at less than 10 inches . My cock gets tiny red ruptures from the pressure of being pumped and the inflated size only lasted for about 30 minutes except for the foreskin...took several days for the donut to disappear entirely and still the foreskin stayed sore for several more days!