What is the meaning behind fall out boys song "thanks for the memories"!

What is the meaning behind fall out boys song "thanks for the memories"?

According to Wikipedia: "a romantic relationship in which the initial sentiments have perished, but both lovers continue to 'sleep with each other' to appease their physical and mental desires." The guy has a one night stand with a girl he really hates and she really hates him, but they do it because they really can't get anyone else at the time. They still have some feelings for each other, but they mostly are just together to make the other person angry and hurt their feelings.

Also, because so many other people have asked this question, I'm going to answer it before you ask it. Everyone always wants to know why it's "HE tastes like you only sweeter" and not "SHE". The reason is that it's supposed to be as though the girl is saying that to him. Actually in the booklet that came with the CD it's in quotes. She is saying that her lover before him has a sweeter taste than he does and that she would rather be with him, but because she can't be with him (her other lover), she'll settle for him. It's taken from a line in the movie "Closer". It really has a very explicit back story involving something other than saliva having a sweeter taste, if you get what I mean. If not, then I probably shouldn't go into more detail. Go see the movie, and you'll hear the line (I've been meaning to forever.) I hope this helps you understand it!