1. Tube strikes.
2. Wanting to use an Uber but the surge price is too expensive.
"The anger of that may cause you to go to a pub, to let off some steam, and you could meet your future wife there."
3. Hearing someone tut behind your back.
"If you are King Tut you would not be upset by that, so it could be just someone recognising you."
4. Going outside for five minutes and then getting the worst tanline.