This discussion may contain spoilers!
So far I've found 9 out of 12 collectibles and figured I'd list them and how to get them (with spoilers, if I can get them to work)
1.Larry Palaroncini - Click on the luxa lounger in the living room of the House of Strong
2.Gary Palaroncini - Use the metal detector in front of Marzipan's house.
3.Perry Palaroncini - Use the Microphone in the front yard of the House of Strong.
4.Mary Palaroncini - Click on the dead fish in the pond at Two-o Duo's stage.
1.Cool Tapes - Click on the left locker at The Track.
2.Two-o Duo - Use the metal detector at Bubs' stand.
3.Pom Pom - Use the Microphone at Club T-C
4.D.O.I. - Use the metal detector at the D.O.I. stage.
1.Cover - Use the "Doin' the Wigglie" record on the Club T-C turntable.
2.Dedications - Use the Microphone at the Cool Tapes stage.
3.Lyrics - Click on the light switch in the computer room at the House of Strong
4.Back Cover - Unfortunately, I don't remember how to get this one, help appreciated.
Obviously, I'm missing tons of info, so I'm relying on you to post more for me to edit in post-haste.