"I want you to say it in Engpsh" in Engpsh could be translated as:

"I want you to say it in Engpsh."

The phrase comes from the speaker's desire for the person they are speaking to to use Engpsh as the language of communication.

Example sentences in Engpsh with Chinese translations:

Can you explain it to me in Engpsh? 您能用英语为我解释吗？
I want you to speak Engpsh with me. 我希望您和我用英语交流。
Please answer the question in Engpsh. 请用英语回答问题。