Ask MetaFilter attempts to answer the question of how to phonetically transcribe the sound of Homer Simpson’s drool. Surprisingly (or perhaps not), this is not the first time this topic has come up on the Interweb; apparently this has been discussed in alt.tv.simpsons back in 2001. Their consensus: “uhhhHHHhhrghhhuuuuHHHggrruhhhHHhh.” 
