When I was a kid, I wore sandals a lot. So much so that my arches came crashing down and I had flat feet. To combat this, my foot doctor gave me these shoe inserts, specially made to help re-build my arches. The problem was that they were foam. For a whole summer I wore a single pair of shoes with those inserts in them constantly.
Fast forward to the end of summer camp, my campers playing 'truth or dare' I dared one of my fellow campers to smell my inserts for 60 seconds straight. He didn't make it. curious, I sniffed it...
Hence it became the worst smelling thing for me, EVAR.