Wait until your punishment is over
From Create Your Own Story
The escape of the boa constrictor earned you your longest punishment ever. By the time you got out of the cupboard, summer vacation had already started. You start to walk outside of your house, for it is the only way you will scape the wrath of the Dursleys. Uncle Vernon told you earlier that you are going to Stonewall High, the local public school. On the other hand, Dudley was going to Uncle Vernon's old private school, Smeltings, so at least he wouldn't be bullied by his cousin.
You remember when he was trotting around in the maroon uniform, when Uncle Vernon was proud, Aunt Petunia was crying, and you were almost cracking up. On the way out, Dudley finds you and says, "They stuff people's heads down the toilet the first day at Stonewall. Want to come upstairs and practice?"