OMG some of these have had me in stitches.
Do not try to reverse your brand new 3 weeks old car to impress some lads in a pub beer garden - you will reverse into a fence and dent the back end of car 
DHs - Do not hold 2 weeks old breastfed baby on knee in between nappy changes it will result in baby pooing down leg, something that relects Chicken Korma
Do not leave a metal tin awkward on the gas hob leaving the handle exposed and try to pick it up without oven gloves
Do nnot try to be the greatest domestic goddess and clean the knife block, holding one knife blade in your hand and dropping it, catching the knife blade with your hand, it bleeds for eternity.
Do not play with with ex knobhead and lean in and let his elbow bash you in the eye resulting in a black eye 4 days before being a bridesmaid at your mother wedding.
Do not play football inside with the kids, especially when the small winnie the pooh ball lands at side of hoover, you will kick the hoover and break your little toe.
Do not bite down on a hard bit of burnt pizza base, it will result in you oving your wisdom tooth out of place and the need for operation to remove the said tooth especially when extremely scared of the dentist
Do not stand talking to mates at petrol station whilst filling car up and not noticing what you are doing and then realise you have just wasted £30 of petrol onto the floor and notihing in the tank. 
Do not leave curling tongs plugged in to the extention then turn on the CD player and turn it off on the system rather than at the wall. My mother didnt see the funny side when it burnt a massive hole straight through to the underlay on a week old bedroom carpet - She will come home from the pub drunk, start shouting at you whilst been 5 months pregnant, then Stepdad starts shouting and DF (now DH0 start fighting over it and it will result in you moving out of your mothers house permanently :(
There are soooooooo many.