When you fight that big black buggy fucker in RE4. He killed me about 5 times before I realized he was invincible, then got me 3 more before I noticed the liquid nitrogen tanks and figured out I had to tip them over to slow him down. Also, that part was scary as fuck.
And then there was that part where the statue of Salazar chases you and you have to fucking BUTTON MASH to get away from it, jesus christ I wanted to hurt whoever thought that part up
I also had some trouble with "It," but that fight was so scary and awesome that I didn't care. :o