"Riddle School 5" is the fifth and last instalment in the "Riddle School" series of point-and-click flash games. You play "Phil," a school escape artist who has been abducted -- along with four of his friends -- by fiendish aliens bent on destroying the Earth. One of the puzzles in the game demands that Phil kill his friends in their dreams to wake them up. Phred is one of those friends, and can be killed rather easily in his dream.
Click the number pad in the room where you discovered you needed to kill your friends in their sleep.
Enter "7272" to enter Phred's dream.
Talk to Phred and sit through the dialogue, then click the Broken Tile item. Phred is now dead inside his dream.