Royal Clipper / Caribbean
When you take your sailing certification tests, they make you demonstrate your ability to tie a series of intricate knots. The important skills required to successfully tie those knots will immediately vaporize from your brain minutes after the exam. The rabbit comes out of the hole and which way around the tree? Which one is the tree and which one is the rabbit?
Thankfully my sailing days are behind me. I'll just stick with this little piggy one or the classic granny knot. But that's as complicated as I get.