Because the censor erased the letter "s".
Somebody told him to get a long little doggy.
He's staring at somebody else's shoes.
Sparky
Bingo.
Chronic-logically.
A few months ago
Ten. Aye, aye, arr, and the seven seas.
Post office.
Gluk gluk gluk (say it out loud)
Who gives a cluck (I wonder if the moderators will censor this joke merely on the grounds that it is categorically terrible )
THE PUNCHLINE OF THIS JOKE HAS BEEN CENSORED BY THE GOVERNMENT OF THE PEOPLES REPUBLIC OF CHINA, PLEASE REMAIN CALM WHILE WE WILL DEAL WITH THE OP IN A CIVIL MANNER.
A: They are the only ones who erase their notebook when the teacher erases the board.