I remember noticing in China that it seemed very common in Chinese casual chitchat, but to Western ears it sounded inappropriate. In the context of a lecture, I imagine it would come down to whether the delivery seemed genuinely part of the point or an excuse to push boundaries. Hard to gauge without audio/tone.
I can’t think of why you’d report this unless you had a serious issue with the lecturer or they were being purposefully inappropriate.
那（nà,that）个（gè,one）。 Also 'umm, uh, like, so'. English has the same thing, for example when you can't think of a word and just start with 'that, those'.
'Eh, what's that.. that, uh, the name of that function?'
It's pretty easy to mishear it, but 99% of the time you can see from the context that they're not just wildly dropping n-bombs..
It's especially bad that this gets pulled up on a lecture about filter words.
If you listen to any native Mandarin speakers for more than 5 minutes you'll likely hear this word. If anything, being educated of it's existence allows you to recognize it as a legit word used in every Mandarin and not freak out when you hear Chinese people talking and think they're talking smack about black people.
There's two ways of pronouncing it, both acceptable in Mandarin. In English they would be something like: "naugh guh" and "neigh guh". The latter pronunciation is the one under discussion.
