People can say it with expression so it sound like "why did do that " like you blame children for something and then people go like "haram alik ". If you scream then it mean litrly "haram "

Haram = Taboo or sin

Haram = forbidden ( logically and in the islamic way ) illegal sex is haram as an example . in other ways , in dialects , it means the same thing but in another way , it's just like why did you do this ( to me , or anything else ) , if you kill an innocent insect , maybe you will hear that one .

you can say " shame on you " or something forbidden to do or to say

Haram in ISLAM means not allowed to do ... When someone tells you : Haram alayki that's mean you shouldn't do that !