So if I see a scorpion, I get silent and try to find a thick, hard, large object to crush it with. Only when I go in for the kill do I scream, and it's fairly involuntary. More of a warrior battle cry, but a scream none the less. A spider will make me gasp, but something like a roach will cause me to do the little girl, "EEEEEEK!" So what critters make you jump up on a table and hold up your skirts?