2. To enthusiastically share details about a current interest which is of little or no importance to your audience.
It resembles an "orgasm of the mind".
Geeking out is not a universal feeling. As a result, if one person in a group geeks out, everyone else is wondering in curiosity what is wrong with that person.
When I saw how all the computers were built, I totally geeked out!
When I heard that he had collected all the baseball cards that I had looked for for so long, and he finally offered to show me that collection, I totally geeked out!