A bitchy nerd. Someone who intensely focuses on any type of work for a period of time, disregarding everything else (including that person's social life).
Michelle did not go to the movies with her friends because she was being a berch.
Don't talk to me, I'm berching right now.
Oh my god, she is such a berch!
Let's berch today :)
I berched all night and I'm just so exhausted.