- Click really, really fast.
- "Well I'll be!"
To obtain Uncanny Clicker, you have to click 15 times a second (150 clicks in 10 seconds).
Strategies
As of the 150/10 sec rate, it's almost impossible to get this achievement the honest way. Only people with very fast clicking can unlock this achievement (function responsible for unlocking this achievement is even called "autoclickerDetected"). The exact rate required has been tweaked multiple times over the development of Cookie Clicker, and may be subject to further changes.
Playing on a computer, you can try clicking with a mouse and tap the left panel (at the bottom of the keyboard) at the same time. It sometimes works if you are fast enough.
If you use a full keyboard (not a condensed laptop keyboard), you can enable mouse keys to roughly double your rate. To do this, you must press LEFT SHIFT + LEFT ALT + NUMLOCK. Then, simply spam 5 and + on the numpad on the far right side of the keyboard.
You can also enable some scripts or otherwise slow your browser down enough that your natural top speed registers higher than it really is.
Cheating methods to get this achievement are simply enabling the achievement with a script, or using an autoclicker.
To see how fast you are, click here. The link lets you see how many times you can click in 10 seconds. If you score more than 150, you may be able to unlock this achievement without any tricks!