When you start reading a thread, and an hour later you see that you've still got over 150 pages yet to read, but there's a comment you want to make, and you're afraid that someone else has made the same comment, but it's not very logical to read the whole thread just to see if someone posted one comment, but someone might think you're stupid, or unmotivated if you were to make a comment that someone has already said, and you might hurt the feelings of that person if you copy their comment, since you obviously didn't take the time to read their post, so in the end, you skip to the end, and make a long explanation in the form of a thread comment so that everyone can clearly understand why you are about to make the comment you are about to make, and just hope that someone else hasn't used the same tactic, and that you're about to copy
their post.
When everyone tries to finish your sentences, but never get it right, but to spare their feelings you say, "Yeah," anyway, and then go on with your original line of thought with, "Also it could be..." Of course, after they've unsuccessfully tried to finish your sentences several times in a row, you just give up as your idea of a perfect conversation begins to fragment around you, and you either clam up, or flat out tell them that you meant X not Y, and to hell with their feelings! Then you find out they could care less if you correct them...