Mentioned before I think, but anyway...
I had a day off school (aged about eight or nine), so my Mum took me to work with her (she was a receptionist) and let people know that if they wanted odd jobs doing, I was available to help.

I ended up with a pile of documents to photocopy, collate and staple together. All was going well until the stapler jammed. So I opened it out, turned it over and squeezed as hard as I could with my thumbs.

KerCHUNK!

Hurray! Stapler's not jammed any more.

Fucksocks*! I've stapled my thumbs together.

To be honest, it didn't really hurt that much but you could see the points of the staple on the underside of my thumbnails. And once it was established that I wasn't in danger of bleeding to death, it gave everyone in the office a good laugh -- apart from my Mum, who just rolled here eyes like Mums do.

* OK this was 30 years ago and I was only nine so probably more like "Blimey!"
( reallywittyname veraciously conspues lexiphanicism on, Thu 20 Dec 2007, 13:39, 2 replies)

Similar
Not worth posting as a new story...

You know when you're on a long phone coversation and it's rather boring you fiddle with stuff, doodle etc. I opted to play with a stapler. I pressed my thumb against the bit where staples come out, and squeeze. One staple stuck in my thumb. Luckily the sides weren't bent around, but it made me finish the call a lot quicker.

I was 21.
( Moonraker isn't the droid you were looking for, Thu 20 Dec 2007, 13:44, closed)

My dear departed mother...
...managed to put THREE staples in her hand using a staple gun -to repeat this feat, hold a poster against wall with left hand, staple in right. Staple from left to right, firing a staple about every half second. Ensure that you traverse said left hand without interrupting firing rhythm.
(Mousy Tongue ...Generally bemused by life..., Fri 21 Dec 2007, 8:28, closed)