How not to parent

I need to learn to interact appropriately with my children with regards to what is polite social behaviour and what really isn't. It's kind of fun to push the boundaries with them and joke around (especially when my tolerance of most things foul is much higher than theirs, so any attempt by them to gross me out generally backfires), BUT when you are dealing with a smaller person who is not aware does not care about such boundaries then my plan should probably be longer term than the next 30 seconds of mirth.

Exhibit A
I am doing pre back-to-school appraisal of uniform /shoes / PE kit. I am two down one to go. I call the last one in to reassess fitting of final item - his coat from last term. I hold it out as he slips it on and we deem the coat still fits. Yay- back-to-school clothing and shoes are sorted! I just need to spend this coming week making sure we are all up and dressed before 11am or Monday will hurt a whole lot more than normal.  I'm about to dismiss him back to Miscellaneous Leisure Activities when...

Me: Argh. Look at my hand! I have one of your bogies on my hand!
J: I don't think that's mine.
Me: It must be mate- how would one of mine get there?
J: Good point. (He turns to leave)
Me: And... I have no tissue. You could just eat it?
(Immediately he sucks it off my outstretched finger then wipes his mouth with the back of his hand).
J: That DEFINITELY wasn't mine...
(He hugs me and walks away).

Exhibit B
Linked to inappropriate parenting issue above, but more about my cooking issues and what happens when I've not properly cooked for almost 2 months (working away /visiting mates & relatives / working away some more / visiting some more) then going shopping without a list and ending up with far too many cornflakes for the cupboard and finding expired food products that make me panic because I have a love/hate relationship with the food bin...

Mid-morning. My mate, her kids, me and 2 of my kids are in her car on way to IKEA. Aside from a vague plan concerning purple curtains and purple accessories, the day has not been strictly planned.

Mate: Have you had lunch yet?
Me: No.
Madi (from back): I haven't even had any breakfast yet!
Me: Why not?! Didn't you have your chocolate crispy cake?
Mate: For breakfast?!
Me: (Defensively) They have cereal in them...
J: I had a chocolate crispy cake AND jelly!
Me: Because there was no room for the cornflakes in the cupboard (stuff sitting out on the counter makes me anxious- she knows this) and the jelly expired 4 months ago and I only found it again yesterday...

I suspect this does not happen in many other houses. Even if it is the holidays.