Taken from the Official Blink182 site

Mark explains the meanings of some of the titles of their songs:

Apple Shampoo
This song is about a girl I had a crush on, and she used apple shampoo, and her hair always smelled like it.

Dick Lips
This song was written by tom, and he had no title for it. The day thatwe recorded it, our producer asked what the title for the song was, and tom had none. On that particular day, I was stoked on the phrase "dick lips," and was calling everyone that name through the whole session. When Trombino asked tom for the title, I suggested dick lips as the name, and tom was stoked on it. We originally were going tocome up with a better title when the record actually came out, but we ended up liking the name, and it stuck.

Emo
Emo is actually a style of music, and we thought this song kind of sounded like an emo song when we wrote it. During rehearsals, wewould say, "Hey, let's play that emo sounding song again." The title stuck.

Lemmings
Lemmings are animals which follow one another and run off of cliffs into the sea to their deaths. The song is about an old friend of mine who expected everyone to follow what he said was correct. Most of the time, what he thought was correct was really idiotic. He expected us to be lemmings...

A New Hope
This is the actual title of star wars. Watch the beginning credits when the words scroll up the screen.

Waggy
I made this word up while belching, and wanted to title a song with it. This was the song that got stuck with that title.