An explanation which is simultaneously being used as an alibi, which although it is valid was not necessary to say as an explanation for any reason other than as an excuse.
Boyfriend : look, can we please just talk about what happened later?
Girlfriend: Yes, and I can't wait to hear your excusplanation about it.
Boyfriend : what's wrong? Why are you mad? What did I do wrong?
Girlfriend : everything! Please explain this <insert whatever made you mad here> to me!
Boyfriend: it wasn't me! I didn't do it! I don't know how it happened! I would never do that! I wouldn't lie! Please believe me even though I can't explain anything ever at anytime nor do I have to because I'm innocent!
Girlfriend: of course, i should have known. More empty excusplanations.