The toilet roll thing from the first page should be international law; one can't pull as well when it's backwards, and the roll's far more likely to need adjustment in that orientation, especially with enclosed dispensers.
When I was a kid, I went through a phase of avoiding stepping on cracks at all cost. Not because I was afraid of doing so, but because it gave me something to do while walking.
Around fourth grade I developed a system:
1 - The right foot should avoid cracks.
2 - The left foot is encouraged to step on as many cracks as possible. Not because it's good to step on cracks, but because Left sucks and Right rules.
3 - If the right foot steps on a crack, it can be nullified by the left foot stepping on an equal or greater number of cracks within ten seconds.
4 - Being the first foot to step over a crack is beneficial. Naturally, since left is the villain here, I try to avoid allowing it that satisfaction.
5 - When cycling, the first foot to pass over a crack is considered as having stepped on it, so it is preferable for the dastardly left foot to be in front of the right when passing over cracks.
6 - Floors with too many cracks (typically floors with small tiles) are generally exempt from the rules and can be treated as if there were no cracks on them. Floors with floorboards wide enough for my feet (like in my classroom) get some minor recognition, but are generally ignored.
Yes, I'm 29 and I still follow the rules far more often than is reasonable. I regularly change my stride or my pedaling rhythm on my bike in accordance with these rules. At the same time, it's more habit than compulsion.
I don't have Obsessive Compulsive Disorder, I have Obsessive Compulsive Tendencies.