Some conventions are not right or not convenient.
* Metric system. To me, we do not adopt it is due to our love on football. "Fumbled at 1.27 meter" does not sound too interesting.
The joke: When we and the Soviet fire the missile at the same time, theirs reaches us earlier due to the no conversions in using the metric system. Of course, it is the slow CPUs in the 50s.
* English's first floor is ground floor and their first floor is our second floor.
* Their date format is "DD/MM/YYYY". Actually for some purposes both are wrong. For keeping track of my tests, I use YYYYMMDD.
* Chinese has a word for 10 thousands. They have 14 billions in population. To us, it is 1.4 billions. Ours is more scientific with a word for every three zeros such as thousand (i.e.1,000), million (i.e. 1,000,000), billion and trillion.