This is a mash up of “opening up a can of worms” (a situation that once started will have a negative outcome) and “doesn’t amount to a hill of beans” (a negligible amount). For some reason, cans, beans, and worms seemed to be mixed a lot. See, for example, my July 21, 2013 posting – “I’ve opened up a can of beans”, or or my December 18, 2012 posting – “That’s a real ball of worms.” https://malaphors.com/2012/12/18/thats-a-real-ball-of-worms/ and https://malaphors.com/2013/07/31/ive-opened-up-a-can-of-beans/. I suppose worms are can be viewed as negligible as beans. Speaking of beans, the Yiddish word for“beans” is “bupkes,” which has been adopted into American English to mean “absolutely nothing.” You’ll hear it at cardgames when a disgusted player tosses in his hand and says “I got bupkes.” A big thanks to Anthony for hearing this one from a co-worker and sending it in!