STEPHEN FRY: Can you think of anything relating to your fingerprints and pineapples?
ALAN DAVIES: Well, they get - they get - they're quite spiky.
STEPHEN FRY: They are spiky, that's true...
TOM SCOTT: I was watching QI one evening
when Stephen Fry said something that really caught my attention.
[laughter from audience]
STEPHEN FRY: It has an enzyme which is called bromelain
and bromelain actually erases and destroys the fingerprints of people who work with pineapples.
It was used as a plot point in an episode of Hawaii Five-0, would you believe?
VIC REEVES: So if I left my fingers in a tin of pineapple rings overnight...
[laughter from audience]
I could become a master criminal by morning.
STEPHEN FRY: It's perfectly possible!
TOM SCOTT: So, I went to my local supermarket and bought a pineapple and four pints of milk.
The milk wasn't anything to do with the experiment, I'd just run out of milk.
My plan was simple.
According to what I've read, most of the bromelain is in the stem.
So I'm going to cut off the top, slice off the spiny bit on the outside, and put the rest of it in here
and grind it into a kind of a paste that I can put on my fingers.
Bloody terrible knife.
It was a bloody terrible knife; never buy Tesco value knives.
The pineapple goo wasn't particularly appealing.
That really doesn't look nice.
Twice a day, and I'm gonna dip my fingers into this... goo
and then, after a few minutes of letting it... steep, I am gonna scrub them with this pineapple.
Tentatively, I put my fingers in the goo. It was... unpleasant.
Ewww...
I think it's just my brain making it up, but my skin feels tight
It's starting to sting a little.
After waiting a bit more for the digestion to happen, I scoured my fingers on the pineapple for a good fifteen minutes
and did the same again the day after. Twice.
Got some sore patches, came up along my fingers last night
but, I think, everything's pretty much okay.
So, I'm going to put them in the pineapple again, watch some TV, and see what happens.
That's actually really nice. It's been in the fridge
Okay, it's been half an hour, I'm gonna try scouring. I'm not really looking forward to this because last time was a little painful.
I've switched to using a dish scourer because the pineapple outer bit doesn't keep that well in the fridge
So, let's give this a try.
It hurt.
Twenty minutes later, just finished, washed my hands, and for the first time I'm starting to think
this may actually, really, not be a good idea.
My fingertips were permanently red. I'd taken off the first layers of my skin
roughly equivalent to first-degree burns.
I'm honestly in... quite a lot of pain.
It's making me slightly irritable as well; it's making me annoyed. I've spilled pasta all over the place
I'm swearing and cursing, and I'm not normally that bad.
And they're stinging pretty much constantly, like I've been hit by a pile of nettles.
And that's from just holding them in midair. If I actually touch anything, like press a key on a keyboard, or...
or do anything, it sends a real shot of pain through. So I've think I've too much too fast.
I'm going to scrub once a day from now on, but when I'm going to bed so it's got time to heal overnight
and so I'm not completely messed up for the whole day.
On day eight, I had a new pineapple, and things seemed a bit better.
So far, they're just... cracked, really cracked.
Hopefully, it's gonna be okay.
Still a bloody terrible knife.
But then, things took a turn for the worse. At four A.M., on day thirteen, I gingerly set up my camera.
There's someone holding a lighter to every one of my fingers.
If I touch anything, or if the sheets on the bed rub against my fingers, it wakes me up again.
I... I... I need sleep.
The next day, I met someone who told me about a man who had tried to remove his fingerprints before me.
And, at last, I decided to stop.
John Dillinger, seen here in an FBI file photo, was a bank robber during the Great Depression.
In a 1935 article from the Journal of Criminal Law and Criminology, professor Harold Cummins,
the father of modern fingerprint science, describes how Dillinger, "applied acid to his fingertips"
It didn't work. It mutilated him and no doubt caused him tremendous pain
but the fingerprints weren't badly damaged; they just healed.
It turns out that, to actually destroy your fingerprints, you have to go down to the depth of about one millimeter.
That's deep enough that you'd need a skin graft.
So, fingerprints can't be removed with pineapple.
There's only one way to actually do it.
AAAAAAAAAAAAAAAAAAAAAARGH! AH!
No, I'm just kidding, that's not actually hot.