The phrasal verb "geek out" means to get really excited about the small details of a subject. Things that people sometimes "geek out" over include:
- comic books
- sports statistics
You can explain what someone is interested in with "geek out over ___":
I used to geek out over music equipment.
People also sometimes say "geek out about ___":
Math is a subject that I can really geek out about.
When people "geek out" together in a conversation or an online chat, you use "with":
I love it when I can geek out with other baseball fans.