the 'b' word

I am always cautious on my kids choice of words. Strictly forbidden words - the s-words, the b-words, the f-words, which they came across while browsing the world via internet. Sometimes they do not know what those mean but they keep on saying them all out loud, merely imitating and making fun.Once warned, berani lah nak sebut lagi.. siap kena cubit kang :D

Adam, when in doubt, always asks if he can say this and that.
Boleh ke cakap quiet?
Boleh ke kita sebut shut up?
Boleh ke bagitau come back here?

Sometimes I find it amusing. Yesterday was one example.
He: Boleh ke kita cakap busuk?
Ai: Boleh lah. Tak salah.
He: Okay, boleh cakap busuk?
Ai: Iyaaa! (with irritated tone)

He went screaming to Iman 'Abang busukkk! Abang busuk! Busuk! Busuk! Busuk!'
A fight followed after.

Ai: Kenapa adik cakap macam tu? Tak baik!
He: Tadi Ummi cakap boleh??