Just misunderstanding social cues. Where I live (Spain), there's a script you're supposed to follow for certain things and newcomers, understandably, don't understand the script. One famous example is buying new clothes. They all look great on. The idea here is that the poor person spent their hard-earned money on the new clothes. Damned right they look great on! Another would be birthdays celebrated in public venues. Perhaps someone you know is celebrating their birthday in a public venue and you had no idea they were celebrating their birthday on that day. You walk up to them and wish them a happy birthday, BUT you were not invited to this celebration. Since you weren't invited you did not come prepared with a present for the birthday person. The safe thing to do is to ignore, socialize with the people you came with, and make like that person isn't even there until they approach YOU. When and if they approach you, you make pretend you're all distracted and you have to be like, "Ahhh! I didn't see you! What's up?" The reason: that person is buying all the invitees the drinks and food. In exchange, the invitees have brought presents. It's a very nuanced and weird situation all of us have encountered. We err on the fear of not having brought a present because we had no idea because we were not invited.