When it starts getting cold outside, spiders start seeking warmth. Like inside your house.

Some houses have light switches in non-intuitive places. This causes you to blindly search the wall with your hand.

These two facts can combine to create the unfortunate result of you fondling a spider.  Obviously the spider also isn’t terribly excited about being suddenly molested, but good luck telling the spider that the groping was unintentional before it freaks out.

Spiders are surprisingly fast for their size.

Before you know it, the spider has skittered behind something and then completely vanishes. And you just know that the spider is planning to drop on you from the ceiling later as revenge.

I’m itchy. Are you itchy?