Joke of the day

Here's a joke of the day when I received an email from a friend, let's called her S. She mentioned something very interesting from our previous emails exchanges with another friend, M. Here's the content.

From: S
Sent: Mailing List
To: XXX
Cc: YYY
Subject: RE:

M, your first sentence took me 5 mins to understand... initially I thought it was a very profound proverb or something... then only I realized it's typo :P

remember 1 think...talk is 1 think..do is 1 think...

--> remember 1 thing...talk is 1 thing..do is 1 thing...

HAha :D

P.S: Can you all catch the joke here??