Breaking the ice!
Being a lecturer at a famous London College, I used to teach English to students from countries throughout the world.
Each session began with a new class of about 18 students who had never met each other before.
To start the class, and to break the ice, I would tell them a little about myself, trying to add a little humour.
And as I was fairly good at guessing nationalities from people's accents, I told them I would go round the class, very briefly chat with each student and then guess that person's nationality. Of course I was quite often wrong and after feedback the result could be hilarious (and just occasionally slightly embarrassing!).
I recall that in one new class there were two young ladies who looked very similar to each other and who looked Japanese. They asked me, "What about us?"
I replied "Firstly, I think you're twins." They looked surprised but replied that I was perfectly correct, and then they giggled and asked: "... and where are we from?"
I answered: "That's easy. You're obviously Brazilian!" At this there was a roar of laughter from the rest of the class - but the girls looked dumbfounded!
"How did you know?" they asked.
"Well," I said, "your looks are definitely Japanese - but your accent is definitely Brazilian!"
From that moment on, I had the class eating out of my hand!
Footnote: I wrote this a number of years ago: The world has changed since then and most countries now have residents from various countries.
Also, nowadays there are strict guidelines and I doubt if my approach would work or be acceptable! And it might even result in a ticking-off - or worse - by the Head of Department!