Badger Expert

A person, usually but by no means always a man, who can be relied upon to hijack any topic of conversation to parade their own knowledge of the subject, however sketchy that might be.

Examples:

Person: This is a great sandwich, is there avocado in here?
Badger Expert: I know a bloke who imports avocados and he was saying that the harvest this year is very poor because of new water extraction rules (continues interminably)

Person: I heard David bought a boat now he has a new job
Badger Expert: I’ll tell you about owning a boat; my mate has two up on the East coast and he says the most interesting thing is (continues at length)

Person: There was a dead badger on the road outside my house this morning
Badger Expert: Badgers, is it now? I read a long blog by the fellow in charge of gassing badgers for the Environment Agency and the thing most people don’t realise is (continues, possibly with diagrams)

For God’s sake don’t mention beekeeping to Julia’s dad, he’s a noted badger expert

I was just telling Merlin about that house we looked at and I got twenty minutes of badger expertise on the finer points of property law