What is something that is pretty much guaranteed to make you jump?

Doorbell, ringtone, neighbor’s loud door shut, firework/explosives.
Anything loud.

Not critters.

Van Halen.

Racquetballs and linoleum.

Loud, sudden noises.
Terence Hill shooting his revolver at my feet.

A spider crawling up my shirt towards my face.
Spiders in general.
Quite a few years ago, I was camping in a cabin my grandfather built. I moved something and a large hairy spider jumped out onto the floor about 2’ from my face. I yelled with surprise, whipped out my .22 revolver and splattered that SOB.

The fire alarm/ smoke detector.

Centipedes. I hate them!

@kritiper shooting at damn spiders, or the spiders shooting back.

Not taking my anti convulsant pills.

That game-winning touchdown!

Bees, I just hate Bees!!

People sneakin up behind me, scares me to death!

Slugs in my salad.

Finding out that my fart wasn’t dry. Jump and duck walk big time.

Pogo stick

Trampoline

The sight of ucme’s beckoning arousal.

@KNOWITALL BOO!
@Pinguidchance Yes, It’s that big you could play jump rope with it…

Well for me, these little shits make it happen.

^I agree. Annoying song.

I can only apologise dear lady for tempting you with the link :D