source of information

I went to see my podiatrist and this is, in concept, what it said on the cartoon picture on wall:

A few things you should know about your period:

1. it won't go away if you stand on your head
2. if you have 22 babies in 22 years you will avoid a lot of periods
3. if you go on vacation it will come with you
4. although PMS, GST and PST sound similar they are of very different nature