Not useless trivia (of which can come in handy winning slabs of beer in pub quizes0 but actual stuff you can do or know how to do but never need to?

I've been driving nearly 2 years and I've reverse parallel parked maybe 3 times if I'm lucky. I've never properly reversed round a corner either. what's the point? you can waste 5 minutes imagining an examiner is sitting next to you watching your every move or you can go: rear view mirror, no kids int he way, reverse....

Someone showed me how he used to tie his boots in the army so if he got hit with a petrol bomb and set on fire he could get the laces undone in one quick motion. The chances of me being hit with a petrol bomb even in a Glasgow housing scheme are very slim.

What do you know that you don't need to know? let's see if we can find the most useless thing.