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 characters and only two syllables. Two-syllable names are exceptionally rare and extremely sought after. Examples of popular two syllable names include Kleenex, Boeing and WeChat.
This domain was first registered in July 2009. Older domains have an advantage when ranking in search engines.