why do boy act tough but are sweet when they are at home?

Sorry to disappoint you. I'm a pussycat when I'm out, too... I suppose, for some, it's the whole macho thing. To me, it all seems a bit "monkeys swinging through trees", and frankly quite pathetic, but then, I was born in the 20th century. Some of these boors obviously weren't!

Well i'm really like that aswell. The difference between the two act is due to the role society expects from man. Man expected to stood still against the difficuties, not to bend against hardness and show not much emotion. So we usually act tough around other people, and show our true selves to beloved ones.