I’ve always been bothered by this rule. When I buy a book from half-price, nothing makes me happier than finding an inscription penned in front - even better are little notes, ideas, analysises, or even doodles scribbled in the margines of the text. It’s a reminder that this book one time belonged to someone else, and they read it, and it inspired ideas and emotions in them. In a way, it connects you to the previous owner.
I write in my books all the time.
I never stick my head out of the car window while driving.
I never run in the halls at work.
I don’t pick things up off the floor and put them in my mouth.
I knew a person who committed suicide by jumping off a bridge. I remembered my childhood training, and did not jump off the bridge.
Apparently, my childhood training worked. Although I do occasionally talk back, and I don’t always clean my entire plate, even though I am fully aware that there are starving children in Africa. It’s just that as an adult I realize that there are logistical problems with getting my peas and cauliflower to Ethiopia in an edible state.
Oh yeah…and one food one…
Never season anything except french fries before taking at least one bite. It’s rude to the chef. The only thing I was ever allowed to salt first was fries.
I never touch the thermostat. I’m not sure what will happen to me if my husband dies first. I’ll probably have to buy more blankets. Or a pair of short-pants.
Dear Abby gave this weight-loss advice: “Regardless of what your mother told you, cleaning your plate is not going to help any starving children in Africa.”
That’s why God invented dogs
Out of the many dogs I’ve lived with, maybe three were any good at cleaning up spilled food. The rest of them got some, but left most.
Among the first against the wall when I take power are those who pour salt over things without tasting. Fries (extruded potato mush) need something to overpower the blandness of their existence. Fries (deep-fried potato slices or chunks) need nothing but a splash of vinegar.
I can’t think of any rules or guidance I still follow - the priority was definitely placed on us thinking for ourselves, and given how differently me and my sisters developed, one set of rules didn’t fit 
Ah, yes, the two cookie rule. I wonder who decided it would be two cookies though? I have college friends, from all over the country, who experienced the 2-cookie Rule, so it wasn’t local to my neighborhood.
Two shall be the number of the cookies and the number of the cookies shall be two! One ye shall not take, unless thou precedeth to two; three is right out. &cetera.
I can’t touch the thermostat, either. I will get freezing and wrap up in multiple blankets before I ever even think to check the thermostat and see if the heater is on. Huge childhood punishment time to mess with the thermostat.
Every other childhood no touch, like the oven or lawnmower, eventually became chores I was required to do, so I don’t have that over any other object.
Don’t bite your toenails!
Mostly food related:
Don’t put food on your plate unless you are going to eat it.
Don’t waste food.
Especially, never ever waste meat (or chicken or fish).
Can you tell my parents grew up during the Depression? I think these lessons are a large part of the reason I find it nearly impossible to push my plate away until I have eaten everything on it. This is especially bad for me at restaurants.
Roddy
As I told my kids- one for each hand!
I never stick my hands in my pockets at work. I remember my Dad and I getting in big raging arguments about my 10 year old self sticking my cold hands in my pockets when we were working. I wouldn’t be ready jump to attention if something needed my hands. He said it makes you look lazy. To this day I’ll let my bare hands turn blue before I’ll put them in my pockets.
Also, when I would load the trucks in the morning with whatever supplies, it was always requested in a base 6 system. Half dozen of these, mate. Three dozen of those, mate. Ahh, two dozen and one from that pile please, matey. I don’t think I’ve bought produce in something other than a multiple of three since. Seriously.
I remember getting a compliment at a pre-built trailer factory once “You’re a machine dude, you don’t fucking let up!” I grinned and hauled my gear up to an unfinished roof and kept working. I thought to myself, shit, I’m still racing with my Father, though I hadn’t worked with him in years. Brought a tear to my eye on that roof.
Never cry over the small things; otherwise, someone’s going to give you something to really cry about.
Stick my hand out the window when driving down the road, lest some evil roadside sign will whack it off.
Sit too close to the television (it’ll ruin your eyes)
Touch yourself “down there” (see #3 above); okay, I think this one is a lie.
“[An autocondimenter is] Someone who will put certainly salt and probably pepper on any meal you put in front of them whatever it is and regardless of how much it’s got on it already and regardless of how it tastes. Behavioural psychiatrists working for fast-food outlets around the universe have saved billions of whatever the local currency is by noting the autocondimenting phenomenon and advising their employers to leave seasoning out in the first place. This is really true.” – Terry Pratchett in Reaper Man
As a professional cook, I’ve noted the phenomenon in many customers, and by comparing their behavior to that of my dad when I was growing up (he drenched everything in pepper), and remembering my mother’s astoundingly bland cooking, I’ve come to the conclusion that these are people (almost always men) whose wives and/or mothers are/were remarkably unremarkable cooks.
Of course, there are those who have become accustomed to bland food for other reasons. When I worked in the kitchen at the local men’s homeless shelter, I was making country gravy from scratch one morning and inadvertently dumped way too much black pepper into it. I could do little to fix it because it happened mere minutes before it was time to serve breakfast. So as the men came through the chow line I warned everybody about what had happened and I clearly and emphatically recommended tasting the gravy first before adding any pepper. Needless to say, these homeless men were conditioned to expect tasteless food in homeless shelters, and I watched with a mixture of horror and amusement as nearly every one of them sat down and proceeded to pour more pepper onto their biscuits & gravy. Which was followed by much eye-bugging, gasping, and chugging water 
“Son, there are three things you don’t fuck with:The Government, Trains and Tornadoes.”
So far, so good.
Napkin in lap. Elbows off the table.
As an adult, I think these are stupid rules. But it’s been burned in my brain and will remain ther until the day I die.
Mm… there’s one about soup, too.
Always bring the soup to your mouth, not the other way around.
… except I never understood why that is… my hand shakes a little, and hot soup + involuntary motions usually end up as hot soup in my lap.
I’ll lean my head towards my bowl, thank you very much.
If you look at the packaging on many cookies, two is the number of a “serving”. Perhaps our mom belived what they read?