I can't take credit for this one. I read a version of it in an issue of Reader's Digest that was old even when I was a kid.
On the last day before Easter break, a 1st-grade teacher asks her kids to write a theme on what they will be doing for the holiday weekend. The classroom gets quiet as the kids get busy writing. The teacher sits quietly at her desk catching up on grading papers.
It doesn't take long for little Johnny to shuffle up to the teacher's desk. He asks, "How do you spell 'gun'?"
The teacher is surprised by this question, but obliges. Her policy is to write on the chalkboard any new words the children want to learn. So she dutifully writes "G-U-N" on the board, leading to murmurs from the class. She quiets them down and goes back to her desk.
Not even a minute later, Johnny walks back up and asks, "How do you spell 'die'?"
Perturbed, the teacher nonetheless writes D-I-E on the blackboard. The whole class gasps. The teacher stares at the two words, and is increasingly disturbed. Finally, as Johnny is about to come up again, the teacher cracks.
"Johnny, look at these words! What on earth are you going to be doing?"
Johnny beamed as he replied, "I'm gun' dye Easter eggs!"