I once almost gave my grandmother a heart attack. I don't remember where I got it, but I had this miniature manilla envelope labelled something like "Danger! Snake Eggs!". Inside was basically a rubber band stretched between two metal hooks. The rubber band passed through a washer and you would twist it up so that as you started to open the envelope it would spin creating a loud noise as it whacked against the paper envelope. I pretended I was scared to open it and gave it to my grandmother to open. Not sure why she agreed to open it but it nearly, literally, scared her to death, lol.

I just searched for it and found it online. I guess the classics never go out of style: https://www.amazon.com/dp/B0D8JB8T3R/ref=sspa_dk_detail_0?sp_csd=d2lkZ2V0TmFtZT1zcF9kZXRhaWw