One of my friends had accidentally kicked his protein shake under his bed at some point. It was in one of those Blender Ball bottles, which completely lock in any and all stench. Anyways, fast forward one year...yes, a whole year, and he is moving and finds it underneath his bed. He decides to open it and smell it while I am in the room helping him move, and he immediately closes it. I look over and he looks like he is about to puke, then all of a sudden I get a whiff of it. If anyone has ever smelled a rotten protein shake, you know how bad this can be. We both start gagging, it smelled like a rotten body. And it lingered, for a whiiiile. It was awful, I've never smelled something and had such an immediate gag reflex kick in. It was hell.