Most of these things learn kids in their schools. I have seen shia kids being bullied for their beliefs in school and college. And to be honest I enjoyed that back then. Well deserved!! That’s what I always thought.
It is the nature of the innocent childern. If they are targeted for something, they try to abstain themselves from the things they are bullied for. It has nothing to do with any inferiority complex syndrome as someone suggested previously.
I remember this one incident. I was in 7th class. It was a cold winter day. For some reason this kid wore a black sweater instead of the blue uniform sweater. None of our teachers objected but as soon as this long bearded wahabi teacher entered the class, he harshly shouted at this kid. "oye tu kiya shia hogeya hay, chal utaar iss kaali jarsee ko"
The way he pronounced shia and kaali was like that these were the most najis words in the world.
He even slapped the kid as the boy was hesitant to take off that sweater. And then he took it and threw it in the corner.
Another one after almost 6 years, in the college. It was the third day of my B.Com class. This long bearded teacher (again 
) who supposed to teach us statistics noticed that a girl in front row is wearing black chaader. The next half an hour he gave us a lecture on black color and how it is associated with shia and muharrum and why one should refrain from wearing it. The foolish girl who was wearing the chaader to cover herself not only removed it in front of everybody but we never saw her wearing black color again.
The actual reason behind this brain washing seems the insecurity of sunnis. They don’t want shia kids telling their children what happened just after the demise of Prophet (s).
I was literally kicked out of a mosque because I was asking a lot of questions. Latter this mullah who shouted “oye eh lagda aey shia hogeya aye, baa’r kaddo einu masjid too” when confronted from my father told him that I can ask those question only when he is alone in the mosque. Never ever should I ask those questions in front of other boys or people. He is totally unaware that this behaviour of his actually helped me with my convertion to shia islam.
I know a lot of people who preferred fiqah Jaferia over fiqah of four iama like myself. Almost all of them were told not to ask too many questions. Not to mix up with shia. Shia are so wicked that they will turn them to shiaism. LOL!
On the other hand I have seen shia ulema encouraging shia boys to attend sunni functions. To go in the sunni mosques for the sake of knowledge. To mix up with sunni folks to know their believes.
This is the best thing in shiaism. you are never forced to accept something as it is. You are free to think and ask. Not like those sunni ulema who told me “yeh to aisa hee hay, humain ziyada tafteesh main naheen perna chaheyay. Jo hogeya so hogeya. Ziyada socho gay to Aimaan daggmaga jaye ga” Or " koi zaroorat nahi hai aisee batein sochnay kee, aisee batain sirf aalimo kay sochnay kee hain. Tum namaz parho aur ghar jao"
And latter after I adopted shiaism this one alim expressed his contempt to my Father" dekha mainay to pehley hee keh diyaa tha, ziyada batein matt pocho. Ab ho gia na shia! Mayree mano to ghar se nikal do" :halo: