TABOO
bleep something out
to replace a word or phrase in a radio or television broadcast with some sort of musical tone. (This is sometimes done to prevent a bad word or other information from being broadcast.)He tried to say the word on television, but they bleeped it out.They tried to bleep out the whole sentence.
forbidden fruit
someone or something that one finds attractive or desirable partly because having the person or thing is immoral or illegal. (From the apple in the Garden of Eden that was forbidden to Adam by God.)Jim flirts with his sister-in-law only because she's forbidden fruit.The boy watches that program only when his parents are out. It's forbidden fruit.
off limits and out of bounds
forbidden.This area is off limits. You can't go in there.Don't go there. It's out of bounds.That kind of behavior is off limits. Stop it!