What is the biggest cultural mistake you've made when travelling abroad?
Tbh I haven't been anywhere that exotic, however in most of Europe, when visiting someone's house you take your shoes off and leave them near the door. Some people have "guest slippers" which are like large woolly socks that they give you. In the Uk we are far less into this. Some people do, some don't, but most wouldn't ask guests to take their shoes off unless they just got a brand new white carpet.
It took me a while to catch on as everyone was too polite to tell me.