"No shit," not just a figure of speech

As an American it's easy to take plumbing, and Western-style toilets, for granted. Flush away, no problems. But the plumbing in China can be hit or miss, so in at least one restaurant there are house rules, and almost all toilets in China are squatters, which explains why Chinese people are so comfortable squatting while waiting for buses, trains, and traffic lights, etc.

House rules: sign in bathroom at Beijing restaurant.

The Chinese have perfected the art of squatting.