"No, It Isn't" is a song written by Mark Hoppus for his side-project +44. It was originally released in late 2005 as a rough mix for free download from the band's site. Carol Heller originally sang backing vocals in this version of the song, but the backing vocals were re-recorded for the final album version. The CDs came free with merchandise purchased from the band's site. The album version has a new drum track, as well as an extra verse at the end of the song, (Please understand... Lay rotting where I fall. I'm dead from bad intentions. Suffocated and embalmed and now all our dreams are cashed in. You swore you wouldn't lose then lost your brain, you make a sound that feels like pain. So please understand, this isn't just goodbye, this is I can't stand you.) that was not on the limited edition single version.

On October 24, Travis Barker (drummer from the band) told on "No, It Isn't":

I have a snare and I just like lay real back, and just play accent things here and there. Originally that was all acoustic and I never wanted to put drums in. I always thought like what Mark was saying and the words, what he was talking about, just stood on its own. There didn't need to be anything else behind it besides him and that acoustic guitar. Then I kind of got outvoted. They like drums in it, so I was like, "I'm down with it. If it makes the song better, I'm gonna do it."

The song was available for download on their official site on December 13, 2005, which happened to be the day the ex-bandmate from Blink-182, Tom DeLonge was scheduled to release material from his new band, Angels & Airwaves, and also his 30th birthday. Hoppus has stated that he didn't mean for that coincidence to happen, it was a decision made purely by +44 management.

Upon the song's release, allegations were made that the song was about previous bandmate, Tom DeLonge. After a period of time responding to the claim with "No, it isn't" (hence the title), Hoppus eventually admitted that it was directed toward DeLonge.