SUBREDDIT: r/tifu
TITLE: TIFU by being rational
POST: So, it's not a big FU but here goes. I'm walking to the front door and I feel a hair brush the back of my bare shoulder. I have long hair and there are usually a few loose strands. I think "it's a spider" and then think "no, it's probably a hair just ignore it".
Now, considering the number of spiders that live near me it would not have been so insane to think it was a spider and start the spider dance. Once, when I was taking the washing off the line I had one fall on my hand. Then two others walked very fast next to or towards my bare feet. My best was when a dead spider fell down the front of my shirt, pausing briefly on its way down to wave hello and brush against my cheek. So I should know better.
Nevertheless I think I'll be a rational human being and realize it is just a hair. I brush my hand over the back of my neck and feel the loose hair pull over my shoulder. So I was right there was a hair. But that doesn't mean there isn't a spider, which is something I neglected to consider.
Then I'm inside and the hair that isn't there now starts moving quickly up my back. I turn my head and what do you know. There is a big brown compact looking spider sitting on my shoulder. It may as well have been waving and saying "well, looks like you screwed that one up".
Because it was so close to my face I tried to blow it off my shoulder, which worked very well. I sent it flying off into space and I haven't seen it since. So looking forward to that, it will probably climb onto my face while I'm asleep tonight.
TL;DR: 
felt a spider on my shoulder. Decided it was a loose hair. Was wrong. Spider now missing and waiting to pounce.