Or just short out the capacitor terminals with a metal object like the screwdriver and you're fine. But still, if you don't do that and you get chocked it will just be a little painful jolt.
But dielectric soakage runs in reverse, too. So even if you short out the capacitor once, it can recover some voltage after days to months left open again. (The energy comes from the molecules in the dielectric relaxing, very slowly.)
This isn't a problem if the designer has put in a bleeder resistor across the capacitor. But some designers are cheap, and don't want to pay the extra few cents to make their products non-lethal to technicians. Some are just stupid (yes, dumbfuck "senior engineer" coworker, I am thinking of you here, you colossal waste of oxygen).
What you want to do is short it out, with a screwdriver or otherwise, then keep it shorted with a gator cable or even resistor. Then you'll be safe even if you set the project aside for a week. Or three months.
I wired up an unwisely huge bank out of them for some fun HV experiments. They were in a shed outside and could self charge to useful levels in the course of a windy day. Dont recall the actual numbers but it could vaporize dimes handily.
Mains filter caps will be lucky to recover a few dozen volts, which isn't going to do much (and inside a PSU, if the voltage is high enough it will try to run and quickly discharge them anyway.)
Maybe I'm just salty about having had this argument too often recently. But I strongly believe that every mains voltage or higher system needs bleeders across its capacitors. If you don't want to pay for the resistor, fine... but leave the footprint for it.
This goes 10x stronger if the thing is open-frame, sits on a bench, and is regularly being probed by engineers. Just put the goddamn resistors in there before someone gets hurt.
Ahem. Apologies for the intermission.
Check for voltage - If not present / marginal, Then shorten, Else discharge through resistor and GoTo Check. A "capacitor discharge tool" automates this cycle.