Haha, this thread has made me giggle.
My DF always:
Weighs anything he microwaves so he can calculate precisely how long it will take
12 hours before we are due to eat a roast dinner, he goes round each person in the household asking them (through the toilet door if necessary) how many roast potatoes they think they would like to eat. He then examines each potato before peeling it and assesses how many pieces he will cut it into so that he can be sure to have precisely the right number at said roast dinner.
When he gets in the car for a journey, however short, he puts his seatbelt on carefully. He then checks, and makes minute adjustments to, the rear-view mirror to ensure optimal visibility. After this he removes his glasses, breathes on them, carefully cleans them, replaces them, takes them off again to re-clean and then puts them on again. When I was 16 and had a Saturday job for which I was invariably running late, this routine used to drive me to tears on a regular basis 
There are hundreds more examples, but I am too tiddly to list them all. I'd think it was an age thing but he's always been like this, or at least for as long as I can remember 