Annie: I've never heard that phrase used that way. I *have* heard "爲什麽不去." (why aren't you going?) but I'm not sure the Chinese have a phrase to indicate approval that way. I guess you could say something grammatically sensible but out of left field like, "不會造成惡性循環, 應該去" Lit: "It won't start a vicious cycle, so lets go." Or you could go with, "怎麽也得吃吧。" Which translates kinda funny into English but "Whatever/Whoever it is, they're gonna eat."
If you do want to entertain some people I learned a related phrase (related to the movie not to your question) from Farewell My Concubine, and I ran with it. It always makes people smile because one it's different from what most foreigners would say, and two it's a bit over the top dramatic. Say somebody says to you, "你有沒有吃晚飯" (Have you eaten dinner?)
I sometimes respond (but not every time otherwise it loses it's effect),
"好像有，肯定有， 絕對有!" (I seem to have, certainly did, absolutely did!" (hao3 xiang4 you2, ken3 ding4 you2, jue2 dui4 you2)
The trick is in delivery, you get progressively certain, so you get progressively more direct and loud. The last three words have to be said almost with as much panache as you can muster. It can be used in any circumstance where somebody asks you if you have or have not done something, or even if you want to do something, just replace "有" with "要"
Which should be especially easy in Taiwan because they have a habit of adding a "有" in front of lots of verbs. People here in Beijing tease me that I tend to do that as well. Thanks Taiwan!
