led strip deadly psu?
12V won't kill you, unless you hook it to a sword and stab yourself with the sword.

As Oli Glaser answered on this question. 20V can kill you, but then you have to be very unlucky and unaware of your surroundings. 

And as GreatScott has shown in one of his videos, he can handle around 60VDC and 20VAC. That's when he pushes his hands flat onto conducting plates => he tries to minimize the resistance. 

But again, 12V will be safe. unless...

Also, you can lick the contacts of the 12V supply, it will sting a lot but you will survive, and possibly evolve into some lightning mutant from X-men. You'll be the next spiderman.