Definition of sperg:
(n) :
(slang, derogatory, offensive) A person who displays awkward, pedantic, or obsessive behavior stereotypically associated with Asperger's syndrome.
(n) :
(slang, derogatory, offensive, sometimes reclaimed) A person with Asperger's syndrome; an Aspergerian.
(v) :
(intransitive, slang, derogatory, sometimes reclaimed) To ramble in excessive detail, as someone with Asperger's syndrome would stereotypically do.
(v) :
(intransitive, slang, derogatory) To have a tantrum or fit of rage.