What is the worst designed everyday object?
I'll agree with the commenter who posted:
The tightly-seamed, clear plastic (blister?) packages in which everything seems to be displayed and sold. Everything even slightly valuable, that is. You know what I mean. Memory cards come in them, as do children's toys and disposable razors. They are designed to make theft difficult, without any consideration of the difficulty they impose on the legitimate end user.
I'm thinking of the time I bought a pair of kitchen scissors and it came packaged this way. I can't open these crappy packages without my kitchen scissors! And, even then, I cut or scrape myself half the time.