#rigging disasters

So I was out on the water last weekend, feeling pretty confident in my abilities... that is, until I managed to get my sails tangled in the rigging. I mean, it was a real mess. I was trying to tack and somehow ended up with the jib sheet wrapped around the mast. I spent the next hour trying to unravel the whole mess, sweating bullets and wondering how someone with my experience could be so incompetent. And the worst part is, it was completely preventable. I just got too lazy to properly secure the sail before turning... what's the most egregious mistake you guys have made while sailing??