I too was going to say microwave before reading the post body. Honestly though anything with a large capacitor, I can’t give you examples unfortunately because I study physics not electrical engineering but some of those fat fucking capacitors will fry you and they hold their charge.

Anything connected to your garage door.

That spring will fucking kill you.

I was actually going to say microwaves, but specifically the thing where people use the parts to make those things where you can burn fractals into wood. They look super cool but apparently if you brush up against the wrong component your heart just stops.

Batteries

Old arcade machines. Giant capacitors + little knowledge on the subject = a very bad time.

As with anything it can be done safely if you know how. People still play those and they obviously need repairs/maintenance sometimes.