Everyone has their own areas of expertise.
Not necessarily something related to their professional field, but more one of their great interests or passions, which they almost unknowingly learned about over time.
And as a result, should said topic arise during a group gathering or dinner party, they'll be able to talk about it for hours.
Much to the delight, or dismay, of their friends and family.
Redditor NikonDexter was curious to learn people's hidden knowledge on which they could provide an impromptu lecture, leading them to ask:
"What topic could you talk about for 30 minutes with no preparation?"
People believe anything I say.
"Anything, as long as nobody’s fact-checking me."- Left_Complaint1604
You think the werewolves in Twilight are scary?...
"Why most modern interpretations of classic folklore creatures, werewolves, faeries, vampires, etc., are less scary than the original stories."- Applesintheorchard
Don't even get me started...
"Why people who don't use turn signals are f*ck heads."- scotsworth
Red Car Headlights GIF by 7-LightsGiphyWhenever I need to vent...
"All the stupid sh*t my coworkers do."- DerpWilson
Tell me it's just a game...
" Video games most likely."
"I could easily talk about one of the Ace Attorney cases for 30 minutes."- zettasyntax
"Warhammer 40000."
"It won't be a quick 30 minutes."- Son_of_steven19
Video Games Game GIF by For Better or for WorseGiphyThe force is strong...
"How f*cking incompetent the Jedi order are."- species-baby
Just listen
"Music."- Love-In-Veinz
Happy Jump GIFVaried interests...
"Metal."
"Both the fabrication material and the music."- Faythlessly
Everyone has a passion that they will never tire of learning.
But, don't be surprised or offended if your friends and family don't seem as interested.
That just means you don't have to pretend to be interested in what they start talking about...
@TweetforAnnaNAFO/X
Steve Urkel Oops GIF 
Moon Walk Dance GIF 
The Office Monday GIF by 20th Century Fox Home Entertainment 