Something tells me this might work better with a metal container as metal containers seem to stay stupid amounts of cold when filled with liquids, also another sort of stupid way to keep cool is to stick cans unopened soda against your bare thighs, blood flows through there rather rapidly and cool your body temp down to more bearable temps, works best on inner thighs but if its really bad double up with cans on the inside and outside of your thighs, but must be bare skin contact