While Bob Geldof's philanthropic efforts remain his greatest contribution to humanity, but he was also frontman for the Boomtown Rats. They had a string of hits in their native Ireland and throughout the U.K. from the mid '70s to the early '80s. Their biggest, "I Don't Like Mondays," was inspired by a school shooting that took place on Jan. 29, 1979.

That morning, Brenda Spencer, a 16-year-old with a history of petty theft and violent thoughts, opened fire from inside her house at students outside San Diego's Grover Cleveland Elementary School across the street. In a 15-minute spell, she fired 30 rounds of ammunition from a semi-automatic .22-caliber rifle her father gave her for Christmas.

Principal Burton Wragg and custodian Mike Schar were killed in the attack; eight children and a policeman were wounded.

Spencer, who had told classmates a week before that she "wanted to do something big to get on TV," then locked herself in the house as the SWAT team descended. The standoff lasted nearly seven hours before Spencer finally surrendered. During that time, a reporter from the San Diego Tribune spoke to her on the telephone. She explained her actions by saying: "I just did it for the fun of it. I don't like Mondays. This livens up the day. I have to go now. I shot a pig, I think, and I want to shoot more. I'm having too much fun."

Watch Boomtown Rats Perform 'I Don't Like Mondays'

Geldof read about the news later that day via Telex machine at the radio station of Georgia State University. The lyrics came quickly, and the song was released six months later. Within a few weeks, it was No. 1 in the U.K. It rose to only No. 73 in the U.S. – the only Boomtown Rats song to chart in America – but it's possible that radio stations wouldn't play the song because of its sensitive nature.

Eight months later, Spencer pled guilty to two counts of murder and assault with a deadly weapon, and was sentenced to 25 years to life. She has been consistently denied parole since 1993, and will not be considered again until 2021.

