Person 1: What's a black hole?
Person 2: Black holes are...um...they're uh...black holes, they...erm...er...
Person 1: You have no fucking clue, do you? You're just using filler words now.
A (generally) teen-age boy who spends the majority of his time masturbating into a tube sock. Sock fillers tend to be socially awkward, often standing slack-jawed while in the presence of their female classmates.
"As the girls' P.E. class ran past, a large number of sock fillers began to shift uncomfortably and mumble to each other."
When a band releases an album where there's only a couple good songs, and they need more to make a whole album, so they make crappy songs knowing they aren't that great just to complete the CD since you need at least around 8 songs for a good CD.
The Shins' new album "Wincing the Night Away" has only a few great songs on it, and around 15 tunes in total, so they make a bunch of album fillers in order to make it a full-length album
"Cookie-cutter" songs used to fill time or pad an album around the two or three hits.
While the lyrics might be good the music itself lacks substance. Filler songs will never be on a greatest hits record down the road. Not even as a joke.