The punchline is too long.
Because he had been told to ice it.
Pupil: You told me to put it in the Net.
From the knights Da-sa(y)-NI! This joke is best delivered verbally.
Because she was a-Kraid to. Now I think about it, this joke is a bit more "Riddle-y," than say an actual joke.
Sorry, the punchline is the joke. If you don't get it, ask your dad.
The punchline
The punchlines were too long.