Points of no return

Just like in Harold & Kumar go to White Castle, there are situations where there is simply a point of no return.

In the movie, the point of no return to go back and get a cell phone (I think it was) was something like twenty feet from the apartment.

Well, I think you basically only have one shot to introduce yourself to someone you see on a daily basis - that is, unless something new happens that gives you an opening comes up.

But in most cases, say, you wait at a bus stop every day at the same time, and there's someone that waits with you at the same time every day, if you don't break the ice the first time you see them, then it will become increasingly awkward to introduce yourself.

In the same vein, if you meet someone and then promptly forget their name (like I often do), with each passing moment that you don't ask for their name again, it becomes increasingly impossible to ask again.

Any other points of no return?