I hate that feeling when you see a bug/spider in your room and even though you've killed it, for the next five hours you could've sworn there was a spider creeping up your shin.
This kind of thing happened to me once. I was on the crapper and felt something on my foot. Figured it was just the pants around my ankles or something. Then I felt it again. I look down, and this HUGE brown cockroach is on my foot. I get wide-eyed and jump up, run and grab raid, kill it, and flush it down the toilet. Had me freaked out for weeks.
Another time, in the same bathroom, I was about to use the toilet and notice a spider coming down from the air conditioner vent on the ceiling. It was tiny but still made me jump.
Then in the same bathroom AGAIN, I get up at 4am one early morning to use the toilet and as soon as I turn the light on, another HUGE cockroach jumps off the side of the doorway, as if to assault me.

Ninja reflexes kick in and it misses.
A few months ago, I'm playing video games and my wife is watching some video with headphones. I pause the game and there's not a sound to be heard...except for the distinct sound a roach scurrying around. It's on the wall that is taken up by several bookcases housing my game collection. I run and grab the bug spray and get the little fucker, then realize that it's going to be a major pain in the ass moving everything should it fall behind the bookshelves. Luckily it sort of sprang off the wall, hit the floor and started running. One more blast of raid killed it. We don't have much of a bug problem in this house, but when they do show up, it always seems to be this kind of shit that happens.

:'(
Back when I was living in Japan, one late fall evening, (Evilbore member) Originalz and I were hanging out, and he asks me if there's a bug problem in the wintertime. I'm like "nope, never seen a one when it gets cold...they disappear!" And wouldn't you know it? I go home around 2am and find a cockroach crawling up the wall as I sit down to use the computer. My wife is fast asleep in the next room where my jacket is. But it's not that cold and the convenience store is right around the corner. They're sold out of bug spray. So I start walking to the next convenience store about five minutes' walk away, and it starts POURING. They have bug spray, so I buy it and make a mad dash for the apartment. I'm completely soaked and spend the next five minutes hunting down the roach and disposing of it.