In Epiphany, my preferred web browser, control-D adds a bookmark.
In Evolution, my preferred e-mail client, control-D deletes an e-mail.
Some combination of laptop slowness, lagging window manager, and bad luck sometimes results in me and the computer having a disagreement over which window has focus, and e-mail gets deleted.
I'd vote for a UN resolution outlawing using control-D for anything except delete.
Luckily, my e-mail setup is resistant to accidental deletions. It's still annoying.
Edit: Old discussion page.