Okay, I can't believe nobody has mentioned the obvious here. Yes, the song was first done by the Boomtown Rats. It is about a school shooting in 1979 where a 16 year old Brenda Spencer shot at kids at an elementary school and ended up killing the principal and custodian and wounding eight children and a police officer. It was on a Monday and she ended up saying "I don't like Mondays". So the song is about looking for a meaning of why somebody would do that because "there are on reason" and so they ask why and the reply is "I don't like Mondays".
Okay, I can't believe nobody has mentioned the obvious here. Yes, the song was first done by the Boomtown Rats. It is about a school shooting in 1979 where a 16 year old Brenda Spencer shot at kids at an elementary school and ended up killing the principal and custodian and wounding eight children and a police officer. It was on a Monday and she ended up saying "I don't like Mondays". So the song is about looking for a meaning of why somebody would do that because "there are on reason" and so they ask why and the reply is "I don't like Mondays".