Is there a Chinese equivalent to the British slang which means not bloody likely?

There isn't one single direct equivalent in Chinese for "not bloody likely" that captures the same level of informal, emphatic dismissal.

However, here are some options depending on the context and tone you want to convey:

Informal and humorous:

* 不可能！ (Bù kě néng!) - This literally means "impossible!" and is a very common way to express disbelief or rejection.

* 做梦去吧！ (Zuò mèng qù ba!) - This translates to "Go dream about it!" and implies that the idea is ridiculous and unrealistic.

* 别开玩笑了！ (Bié kāi wánxiào le!) - This means "Stop joking!" and suggests that you don't believe what the other person is saying.

More emphatic and negative:

* 想都别想！ (Xiǎng dōu bié xiǎng!) - This translates to "Don't even think about it!" and is a strong way to express refusal or impossibility.

* 门都没有！ (Mén dōu méiyǒu!) - This literally means "There's not even a door!" and suggests that something is completely out of the question.

* 简直是痴心妄想！ (Jiǎnzhí shì chīxīn wàngxiǎng!) - This means "It's pure wishful thinking!" and implies that the idea is delusional.

Remember: The choice of phrase depends on the context and your relationship with the person you are speaking to. Using more informal and humorous phrases is appropriate with friends or family, while more emphatic and negative phrases are best reserved for situations where you want to be more serious or assertive.