As a lad from essex you have to imagine these said with an essex accent, or rather , sed wiv an Essix Acksent.
Dont sit so close to the fire you'll get corn beef leg - true the blood vessels dilate and over time do stay that way and ends up looking like corned beef.
Dont sit on a cold floor you'll get farmers. Farmer Giles - Piles and again true I believe.
DONT SAY BLIMEY it means Blind Me and you dont want that.
DONT POINT ITS RUDE - in fact this is to do with witchcraft and cursing. Two things were needed to form a curse, a pointed finger to focus the will and energy of the curse, and a mouth to voice the curse. Also joins with, a pointed finger held over closed lips, a sign of I WONT TELL or MUST NOT TELL. In fact not sending out a curse or holding one back and also in modern day witchcraft you see a wand, this is an extension of the pointed finger.
DONT EAT APPLE SEEDS - they grow in your belly and you'll die. No but after a sneeze and eating tomatoes a few cases have been found where a tomato seed has germinated in the forehead sinus. Not good.
DONT pick your nose you'll unravel yourself. Or - you go any higher you'll push your hat of. If its the other end it was "cough - erm is there a hair in your mouth?"
Carrots - help to see in the dark - true
Pees - green nuts - true
Dandelions make you wet the bed - potentially true as they contain a diuretic.
Dont eat crab apples they will give you stomach ache - nope false
Dont eat cheese an hour before swimming - you'll drown. False lol
Dont eat raw potato it gives you worms - unknown oooooooooo
When talking to my mother about this family tree stuff its - "oh right more Hatches Marriages and Dispatches is it?"
Clean your hands and under your nails else the grave diggers will get you if you have hands like them.
Dont touch the fire you'll get burned - as it turned out, true lol
If you eat all your greens you'll grow up to be a big strong boy - as it turns out I grew up to be a big fat boy who likes greens as well as sweets and chocolate and pies
Dont pick your nose and eat it if you do you will die. "Where do I put it then" - Just dont pick your nose at all. "daddy does" SMACK!! "OK sorry mommy"
Dont swallow chewing gum it goes into your insides and goes round and round and round forever. No - but it is a cause of diverticulitis (pockets on the bowel wall that fill up and get infected)
Dont tell lies you'll get spots on your tongue.
IF YOU DONT STOP DOING THAT THE - - - - MAN - - - - - will come out and tell you off. This man was who exactly, but he was everyhwhere we went and was always watching.
If you are naughty I will always know.
Never put anything in your ear smaller than your elbow. Tried this with a small magnet. After an hour of laying in dads lap while he probed my ear with a pin and managed to get it out I obeyed this rule.
Hope you enjoy my abused childhood lol

I did.