Or a social one. A type of Murphy's law. Share patterns you actually observed in your life.
I based mine on actual patterns.
Jacobsen's law: when you want to kill time by counting cars of a given colour or walk home and need a lift, barely any cars will pass by. But the moment you decide to cross the road there are suddenly four speeding cars on each lane coming from both sides.
The millennial law: the harder you work, the more you get abused and told you're lazy to spite you into working even harder. It is also done to prevent you from realising your true value as an employee and leaving for a better paid job.
The clown law: the effort you put into impressing your crush is inversely proportional to its result.
Example. I was wearing a suit and saw my crush near the stairs so I straightened my back, put chest out and did a cool, confident walk by. But the end of my belt slipped through the gap between my shirt's buttons and protruded ououtward. With every step it swung wildly from side to side like an exposed, erect penis. Of course, I noticed this only after I did my (f/c)ool walk...
Spiteful genie law: the more you want something, the more the universe will strive to make sure you don't get it. To add salt to the injury you often get it only after you stop caring about it at all.
Known from Monster Hunter where you could spend hours without getting a crucial item. Gamers say the game has a telepathic ability of knowing when you want it and makes sure not to give it to you even though the algorithm is completely random. The game's designer laughs at the notion of a game telepathically knowing your desires but admits he himself went for half an hour at a time without getting the item he needed.
Real life example: my grandma wanted to sing in a local church choir. Tried and tried to get in. Eventually gave up. Then, after she got old, an invite to the choir came through the post. By that time she gave up on it and lost interest in it. Still accepted it though but no longer for ego reasons.