One habit which everyone does is licking the yoghurt lid. We all do it, and we can't help it...they only ever give you such a small amount of yoghurt per pot that we try to savour every last bit of it. Yet in public no one does it..perhaps we feel it is wrong and not elegant. Next time you see someone eating a yoghurt, look to see if they lick the lid..especially if your in public.
Taking out the bins...you know its your turn next time it fills up to take it out. So what do you do..? You keep piling up to the other person caves in and takes it out for you. Yes it is harsh and unfair on them...but hey you didn't have to take it out and smell like wet fish for the next hour.
This is an odd one... but it's not washing the colander/sieve. Why...? Because you realise you only just poured some pasta or rice into it for the total of 2 seconds, and quickly flipped it back into the saucepan. One reason why it's acceptable is because you usually are pouring hot/boiling water through it..so surely it is technically clean..Right?
Wiping it on someone else.. It doesn't matter who you wipe it on, the rule is..get it off you and run. From bird poo, to snot to sweat and grease. The sooner its off your hand..the better it is.
Ideal places for this.. the back, the the arm, someone else's bag.