Adventure Time Ukulele

1) the party poppers are clearly visible, so it's not going to be a surprise.

2) The pictured Party poppers are not "pressurized confetti containers", they are powered by a very small amount of Armstrong's Mix (a highly sensitive explosive) in the neck of the bottle-like shape.

I knew a guy who was an animator before digital and he punched a lot of pin-registered holes in a lot of sheets of animation paper in the course of his work which means he always had a ton of 'confetti' around which he used to hide in ingeniously mischievous places. One of the better ones was on a rainy day he'd fill your push-button, spring-loaded, automatic opening umbrella with it.