A word used to make up for gaps in conversation, when the speaker is not certain what they want to say next. Can be very annoying if used excessively.
Prime examples include: er, um, erm, and uh
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.
An internet connection that is very laggy or even non-responsive. The phrase is usually used in Real-Time Strategy or MMORPG games online. The phrase was first used in a 2v2 match of Stracraft when the game was close to lagging out or disconnecting on a host game. When the game dragged, the host saved the match and titled it "WHO HAS THE FISHER-PRICE MODEM!?!". After that, hilarity ensued and the culprit with the slow internet connection was revealed because Starcraft drops laggy users when a game is saved.
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