Drinking From Red Solo Cups
Solo cups are the first thing you associate with colleges and parties, but why not just drink out of whatever container your beverage came in? Solo cups are also a sneaky way to drink-shame people into not sharing what specifically they're consuming. If you don't want to drink alcohol at a party, pour some soda in a solo cup and you still look cool.
Wearing Swimsuits to the Beach
This seems like a no-brainer, right? Wrong. In most countries, people go to the beach wearing next to nothing. Americans are pretty modest on that front, and people traveling into the states have to be warned about wearing clothing while going to the beach so they don't break any laws.