Why YSK: No sense in making the locals mad unless you mean to. In some Middle Eastern countries, a thumbs-up is comparable to the middle finger. A peace sign in the UK is OK if your palm is facing away from you; otherwise, it’s an insult. Pointing with your index finger is offensive in Malaysia. An OK symbol is not OK in Brazil, it’s that smelly hole you normally sit upon.
Reader’s Digest did an entire article on these gestures: https://www.rd.com/article/common-hand-gestures-rude-in-other-countries/
A shaken open hand in Vietnam means it’s all gone - empty. Like I rattled the can and it’s definitely finished. But an American would think it’s a basketball or globe spin thing going on.
If someone picks their nose slightly and flicks it it’s just means get lost. It’s not a drama to them because running noses and boogers aren’t as common in a tropical country. They don’t get plague vibes from everything booger related. Usually it just means your joke sucks.
An intro nodding forward is saying hello with respect, almost like a fist bump with Americans. Folding your arms for older people and slightly bowed nod is double or triple respect. But with most people just return the slight respect.
Use two hands to pass business cards and bow a little or else you’re not really considering them as business clients of any renown. This is the same in all of Eastern Asia AFAIK.
Take your shoes off! Huge mistake in some houses.
Don’t stick your tongue out or use middle finger. It’s viewed as much worse than foreigners expect it to mean to locals. Like you’re defaming them or something.
Don’t pat people on the head in South East Asia unless you know it’s okay with everyone including bystanders. The temple of the body or something to some people.
Some people don’t like seeing kissing in public.
Girls with midriffs/exposed bellies used to piss old men off. Don’t know if that’s still a thing.