A combination of the words "pub" and "bug" make a great 6 letter domain which could be a reference to publishing bugs (as in software) or getting the bug for drinking in pubs.
The word "pubbug" contains only six letters and just two syllables. Two-syllable names are extremely rare and highly valuable. Two syllable names are used by established brands like Dropbox, Subway and Gillette.
This domain was first registered in July 2009. Older domains have an advantage when ranking in search engines.