Over ten years of teaching, I've heard dozens of excuses for misbehavior from students who think they're uttering such phrases for the first time. Here are a few "golden oldie" favorites, followed by my translations of them.

"He hit me first!" (Because somebody transgressed against me, it's fine for me to retaliate in kind, rather than come to you first as I know I should have done.)

"He started it! Why aren't you punishing him, too?" (I know I'm getting punished for not minding my own business as I should have been doing, so I'm going to drag somebody down with me.)

"Billy was doing the same thing a minute ago, and you didn't get after him!" (I admit I'm misbehaving, but since somebody else did it first, that validates my actions.)

"Why are you always picking on me?" (I've gotten away with all sorts of misbehavior before. Why are you calling me on it now?)

"You never told us we couldn't do that!" (I thought that ramming my fist into a nearby student's face was part of classroom procedures.)

"I'm going to tell my mother!" (I'm making a minor effort to intimidate you, in spite of the fact that my mother has never shown up for any of the parent conferences you've scheduled with her.)

"You ain't my mother!" (And aren't you grateful!)

Then there are the endless variations on "I wasn't doing anything," usually issued by the one student in class whom you can count on to *be* doing something wrong, no matter when you call on him/her.

"I wasn't doing anything!" (...including what I was supposed to be doing instead of misbehaving.)

[after being asked to move to another seat] "I wasn't doing anything!" (Even though you didn't ask what I was doing, I'm going to issue a blanket denial in an attempt to get you to focus your attention on somebody else.)

"I wasn't doing anything *that* time!" (I've misbehaved similarly in the past, but you caught me at the one time I wasn't.)

And finally, let us pay tribute to the student who takes his/her own sweet time leaving the room after you've instructed him/her to leave the room with a discipline referral. A few minutes ago, the same student was expending raw energy to chase another student around the room. But as soon as (s)he is reprimanded, suddenly (s)he is the model of etiquette, spending five minutes daintily collecting books, pushing the chair under the desk, and re-reading the discipline referral for possible spelling errors. And if you dare to reprimand this student again, (s)he will say, "I'm leaving, already! Can't you see that?"