Despite both belonging to the subculture scene of Copenhagen, Denmark, the two had never met before, but they became friends over their mutual interest in alternative music.

In 2000, Day recruited two friends, Mille and Kamilla Vanilla, co-workers at the body piercing shop she worked at to act as go-go dancers for the band's live show.

The Offspring was just about to head out on their month-long European tour and with a three-day warning HorrorPops got offered the chance to join them as main support.

Horrorpops played every night for audiences numbering between 5000 and 16000 people, and then continued with their own 1+1⁄2-month headline tour in Europe.

Shortly after the European tour ended, Horrorpops returned to the states to play Jimmy Kimmel Live and a few California shows, but realizing the work that lay ahead and how time-consuming the band had become, Mille had to leave the band to go back to school.

The band's second album, Bring It On!, was released on September 13, 2005, and featured their new rhythm guitarist, Geoff Kresge.

On 23 December 2010, Patricia Day filed a lawsuit in an Indianapolis federal court against the Hard Rock casino, charging infringement of the right of publicity and false endorsement.

In her lawsuit, the HorrorPops singer claimed Hard Rock and Mattel had been selling a Barbie doll in her image without her authorization.

"If we decide to do a comeback tour after a 9-year hiatus, a pandemic will shut all shows down and remove all means of income.