It's a year-end prank that could have been deadly.
Someone spread peanut butter on door handles and greased the floors of Senator O'Connor College School near Lawrence and Victoria Park on Wednesday morning.
The mess was so big, the school was closed down while officials scrubbed and cleaned.
"It's a prank that has gone awry" said Board spokesperson John Yan.
He says anyone with a peanut allergy could have easily been killed, had they handled the peanut butter.
And someone could have easily slipped on the cooking oil.
"It was spread throughout the school, on floors on steps, in the bathroom almost every nook and cranny of the school was covered."
The school is expected to reopen as usual on Thursday.
As for who was responsible, the prinicpal is still looking into it and is conducting a full investigation.
"The appropriate disciplinary action will be taken if an when we find out who is responsible." says Yan.