[bluesroo]

The parent comment died while I typed my response, so I'm just throwing it here to elaborate on your comment:

I'm not Indian, but I read a lot about this when the Cisco stuff came out. The gist that I picked up from interviews with Indians dealing with this was that there is A LOT of cultural background that you'd be very unlikely to know if you hadn't grown up in a certain caste.

A (likely shitty) analogy: You can learn about WWII all you want, but unless you were deployed it would be hard to fake that you were at a specific battle or did a specific training. There's probably minute details that were not written down, but people who were there would casually know. There may be habits or turns of phrase that would have been picked up. Maybe a certain landmark or destroyed thing that had a funny nickname. Maybe it's knowing a certain soldier or commander by a nickname that hasn't made it into the history books. "Oh you trained at X? Man I loved tuna Tuesdays even though noone would touch the stuff. Do you remember when private Y did..."

Through casual conversation, it's very difficult to keep the ruse up. Now if the interlocutor is actively trying to root you out its basically impossible. In the interviews I was listening to, the best case scenario was that the higher caste member came away not knowing what caste your from, but definitely knew you were not a Brahmin... Because if you were, you'd casually bring up X, Y, and Z and use these phrases and these gestures and and and...

[shostack]

Reminds me of how in Inglorious Basterds they gave themselves away by how they gestured the number three with their fingers vs how Germans did it.

[hawaiianbrah]

That’s exactly what I was thinking of, too!

[moron4hire]

Shiboleths

[moab]

It's spelled "shibboleth". You could have googled it.