What’s something in the US that’s considered “normal” but completely confuses foreigners?

I was talking to a friend from Europe and realized how many things in the US feel normal to Americans but probably look strange to everyone else

For example:

• Huge portion sizes at restaurants
• Tipping culture everywhere
• Driving everywhere, even for short distances
• College football being treated like a professional sport

What’s the most “only in America” thing you’ve noticed either as an American or as someone visiting the US?