We've all had substitute teachers before. The school day is often chaotic enough with a good sub, little actual learning takes place, and almost no work gets done. But what happens when the person in your classroom isn't the assigned sub?

At Milwaukee's Rufus King International High School, that was the case on September 24, when 23-year-old Amy Jones walked into the school — where she was once a student — and posed as a substitute. When she showed up at the school, only seven of eight substitutes had signed in for the day, so Jones took the last slot.

Why? After being arrested, Jones told authorities she "was board," that she "hates kids," and she wanted to "f**k around."

It wasn't the first time Jones showed up at the school. She had previously slipped past school security and blended in with students.

Here's more:

Recommended
Here's One Account of What Happened at That Cornell Frat House. This Will Likely Get Messier. Matt Vespa Barack Obama's Campaigning With El-Sayed Just Turned Very Awkward Matt Vespa

She then accused of returning on a day when eight teachers were absent and ‘got lucky’ as only seven substitutes had signed in, before going to a classroom set up by another teacher, who stayed with her for 20 minutes.

However, after that teacher left she allegedly proceeded to organise students by race and gender, insult them using racial slurs and derogatory statements, and use explicit language — as well as playing loud rap music and bragging about being OK with going to jail.

A 16-year-old boy in the class told authorities that she also called one student ‘fat boy’ and told two white pupils that ‘they were the type to start school shootings’, Independent reports.

Meanwhile Fox6 News Milwaukee reported that Jones was said to have asked if any of the students had a vape or marijuana as the class ‘was so f***ing lame and annoying’.

According to The New York Post, Jones is also bipolar.

She was in the classroom for three periods before students reported her to officials, and someone figured out she was a fraud. She reportedly divided students up by race and gender while calling white kids "motherf***ers" and asking one student if they wanted to be a "stripper or a hooker."

Rufus King principal Doreen Badillo admitted school employees "did not follow proper district protocol in validating the individual as a substitute teacher" and that the school was reviewing its safeguards. Badillo also called the incident "disturbing."

Jones is being charged with impersonating a public employee and five counts of exposing children to harmful descriptions. If she's convicted, she faces up to 21 years in prison.