What hand gestures or signs are acceptable in some countries but offensive in others?

I know that showing the palm as a means to say hello is an insult in Greece. If i'm not mistaken it means throwing/smearing mud to someone's face.

Thumps up means its all good or ok

in Thailand some says its very offensive or childish

Hand gestures are a great way of reinforcing what you’re saying, but caution…as they may mean different things in different cultures.