When you interface with any kind of computer that requires manual input (whether by keyboard, or a touch screen) there is the chance for making a mistake. Such mistakes are playfully called "Fat Finger Disease".

我们在操作需要手工输入的电脑（不管是键盘还是触摸屏）时，总难免会出错。这些手工输入时犯的错误就被戏称为“胖手指病”。

Fat finger here refers to the act of performing a typo, often used when referring to password typos.

这里的“胖手指”指的是输入错误，通常用来指密码输入错误。

For example:

You didn't get my email? I must have fat fingered the address.

你没收到我的邮件吗？我一定是输错地址了。