@pdurrant
Try coming to a meeting at work right before it's half way through and see what your boss will tell you and how he will react to the excuse: "but you said to come at the beginning", then cast a glance on your watch, tap on them a couple times and say "and according to my watch the meeting is still at its beginning."
Or when fooling around with your GF (spouse), cool it down right after you've moved on to the second half and declaim: "the end" and see what she's got to say to that.
Can you see now what a twisted logic that is?