What’s the dumbest-nerd-thing you’ve ever done?

Ok, here’s mine;-)

First time took trip into town on my own. Parents told me to take the bus “at
the end of the road”. I waited for ages and all the buses were going out of
town. So went back home. Parents explained I needed to cross over to the other side of the road to get the bus going into town. (Maybe I thought I was in the US?).