"No Homework Pass" joke

Little Johnny Clever was in Mrs. Gleason's 3rd grade class for just a couple of weeks when he ran home to his mom and showed her a little 3x3 piece of paper. It had the word "Homework" crossed out in a circle with a slash (the very same you see with no smoking signs)
"What is this?" The mother said inquiringly.
"Its a no homework pass mommy! I raised my hand the most in class. All you have to do is sign it and I dont have to do any homework for tonight!" says Johnny excitedly!
'Well thats a good thing to keep kids interested in the subject and class participation. I bet this teacher's been teaching for quite a while!' thought his mother as she signed the slip for him.
So the next day Johnny comes home again just as excited. He won another no homework pass. His mother was starting to be very proud. This happened every day for the whole nine weeks.
On report card day, Johnny came home with a D and she started to wonder if maybe he shouldnt be given so many no homework passes but when she asked him about it, he said that the tests were just very hard.
"Well that's allright Johnny, mommy didnt do very well on tests when she was a little girl either. But thats why you have to do your homework to keep up the test grades from making you to fail."
The same thing happened all next nine weeks with the no homework pass, and Johnny's mom was sure that her little boy was going to get an A next report card. She started bragging to all her co-workers just how well little Johnny was doing. Johnny's dad was hearing the good work that his son was doing and was boasting to all of his co-workers as well. At the end of the nine-weeks, they both decided to have a party and let everyone see the big improvement their son was having from bringing that C up to an A.
On the big report card day, Mom and Dad were laughing and having a good time when Little Johnny came in the front door and saw all the guests his mom and dad had. Taken aback by this, he asked his mom what was going on.
"This is for you honey! for doing so well in school! Show everyone your report card!"
"Um mom... my teacher wants you to call her first before you open the report card?"
"Oh?" she said? 'She must want to tell me what a great job Little Johnny's been doing!' she thought... so called the teacher and put her on loud speaker for everyone to hear.
"Ahem, Mrs. Gleason? Hi! This is Mrs. Clever! Little Johnny's mom! Im so happy you wanted to speak to me about my little boy!" exclaimed Johnny's mom.
"Mrs. Clever? I'm not too sure what you're talking about... Did you see the report card?"
Thinking this was the big moment, and she opened up the card to see the big F that Johnny came home with. Obviously getting upset at the teacher because she knew immediately what happened... she spoke back very flustered.
"Mrs. Gleason! I am appalled! If johnny wasnt doing so well, why did you keep giving him the no homework passes that I was signing??"
"N-n-no homework PASSES?" a chuckling Mrs. Gleason started... "no no no... They're no homework SLIPS, when the children dont do their homework! they have to get them signed and bring them back!"
"....oh really..." Mrs Clever started to eye little Johnny as he started backing away...
"You mean to tell me that he's been telling you they're no homework passes?"
... So the next day, Johnny couldnt sit down very well.
... and the next day after that, Johnny had his homework.