You know when you're in a bathroom stall where there's multiple stalls and it's eerie quiet? Well I am always frightened that someone or someTHING will grab at my ankles.
Also, roaches. Really big roaches. I have kind of a gross creepy story about this one. It was about 10 years ago summer, boss on vacation. At the time my work offices had an unused darkroom where I would change for lunchtime workouts. The building was also older, built in 1970, and you'd occasionally see these GIANT roaches running around.
One day, come back from my lunch workout, go into darkroom and throw my clothes back on, including my shoes (these were clunky red mary janes).
Walk out, go back to my work area, and I start to feel a wriggling in one of my shoes. Immediately I know what it is and I SCREAM. Like a horror movie scream. I rip both my shoes off, I see the ginormous roach out of the corner of my eye and I start running around like a crazy person yelling incoherently. The video guy across the hall heard and came in to check and I could barely squeak out what was wrong. Thankfully he killed it for me. So. Frigging. Gross.
Needless to say, I wore my runners the rest of the day. And I never wore those mary janes again.
(ETA: The building i work in experienced a fire about 2 years after this incident, and since asbestos was discovered they did an abatement so the whole building was gutted. No more roaches on steroids!)