kryptonite
n.— «The same things that lowly Washington and freshman Jake Locker used to throw a serious scare into the Trojans. The same things that one USC player referred to as the team’s “kryptonite” in the days leading up to the Rose Bowl.» —“USC defense is catalyst in Rose Bowl win” by Todd Behrendt Fox Sports Jan. 3, 2008. (source: Double-Tongued Dictionary)
Further reading
Katie in Everett, Washington, is curious about the expression If ifs and ands were pots and pans, there’d be no need for tinkers. What is a tinker? She heard this phrase on the television series The Gilded Age, in response to a character who...