Things I don't understand:

1)  Anything that's even slightly scientific?

2)  Why people choose to work in Law or Insurance?

3)  Why ex-boyfriends go on to live perfectly happy lives even without me?

4)   Why tampons are not free?

5)   Why we don't get a pay rise every 3 months?

6)   How some girls are thin but have large breasts (there's a rule, isn't there)?

7)   What people in computers actually do?

8)  How to be easy going?

9)  How to stay close to someone that doesn't call me at least 3 times a month?

10) How to convince someone to marry me? 

These are just 10 out of 10000's  of things I don't understand, wanna share yours?