The average ejaculation quantity ranges from 2 to 5 ml and the average male height 5 feet 9 inches, or 69 inches. So assuming Garfield is the same height as the average male, we can divide his height in inches (600) with 69 inches, (giving us 8.695652173913043 inches) and use this number to as the ratio of ejaculation. So assuming you give great massages, we can safely multiply 5 by 8.695652173913043, which is 43.47826086956522 ml. This means that a 50-foot Garfield would produce around 43.4782 milliliters (~0.0114 U.S. gallons) of cum when tickled in the prostate.