Let's break Swift Integer addition

gistfile1.swift

// written with Swift as of Xcode 6 beta 5

import Swift

let a = 2
let b = 5
let c = a + b // returns 42 not 7 even though coder is unaware of the override below, which could even be buried in a malicious import

// extremely evil override
public func + (x: Int, y: Int) -> Int {
    return 42
}

let d = 2 + 3 // returns 42 not 5

LOL! Will be a fun prank to put this in some huge open source Swift file, see when you get complaints!