I don’t think this can actually be translated back into English… but anyways:
非死不可, to me, sounds like shortened version of 你非要死不可？(Why do you want to die so much?)
Lol I remember I used to make a lot of cross-language jokes as a kid and new immigrant…
Why do you [use] Facebook? --> Why do you 非死不可? (Why must you die? / Why must you use the website that makes you die?)
Oh I just searched Wiktionary, apparantly it’s an official entry… so it’s not just me with this joke lol
「你有非死不可嗎」是無效自殺防治標語；「我沒有非死不可」是嫌犯請求減刑的說詞。
我只有在2016年買的通訊紀錄簿中，看過這個詞，因此推斷，大家都用臉書或者是FB等稱呼，沒想到真的有人非死不可……