it should be habit that when you get up to leave your computer, you mash your lock buttons, whatever that be for whatever OS you're using. otherwise, you could get poopfingered. back in college, whenever someone would get up from the computer lab without locking their machine or in their dorm room, people would send out mass emails to the entire campus raging about something, and then at the end just type "poopfinger" and you'd know that the person didn't really send it, it was some anon that used their logged in account.