I used to use a mac and work and PC at home. My work mac had a feature where you move the cursor to the top right of the screen to wake up and display all your open windows, so I'd just get in, sit down, and push my mouse over as I set down my purse, etc.
But then every time I sat down to my PC at home, which was on a much smaller desk, I'd do the same move and basically sit down, adjust my chair, and knock my mouse right off the desk. Every day.
Now I'm forever pushing my mobile around on the desk annoyed that my cursor won't move.
--
Another one I do constantly is go to grab something off a shelf - looking right at it, watching my hand reach out and pick it up, walking away with it - only to discover, usually much later having settled down to enjoy whatever it is, that I've actually picked up the completely different item next to it.
--
My best one by far, however:
DH and I went to the chemist to refill a regular prescription, gave details, the girl couldn't find the prescription. Tried my name, his name, old addresses and phone numbers, typoed spellings, and nothing. Well wtf? DH and I are both adamant with the girl - genuinely on the verge of steaming by now - to please look again, I know we're in there, as this is where we come every month and have done for years.
Nope! Neither of us had ever once so much as entered that shop before in our lives, AND it wasn't even the same chain as the one that does our prescriptions! (Never been back since, either!
)