My hardships in Japan

So, you would think that bodylanguage was international, right? Well, it’s not.
I’ve often been waved at by otou-san. You know, a wave at the wrist; one you would typically use when waving away a fly or something. Instinctively, you’re likely to think that it means (when done towards you) “shoo” or “go away” or something like that, right? At least that’s what I thought, BUT – it’s actually reverse here! It means “come for a sec” or “follow me”, and even though it’s been done to me a hundred times, I still instinctively register it as “go away”.

Another thing I first didn’t quite get (as I’m self-taught in Japanese) was the word “iru”. “iru” is mostly used as the verb “to exist” for animate things (living, moving thigns), and “aru” is the same verb, but for inanimate things (material stuff). Hence, I was very confused when otou-san, on my first day, asked “mata iru?”, with “mata” meaning “still”, so I translated it as “is there still (something living)"?”. No, it didn’t make sense to me. When he then pointed at the food on the table and asked again, I got even more confused, as I thought “iru is used for animate things; what’s going on here?”.
I didn’t really get the meaning of the “iru” until I heard one of the children responding to the same sentense: “iranai”, which is the negative of “iru”, and a word I’ve heard millions of times in anime “I don’t want/need it”, and so it all cleared up; “iru” also means “to need”.