Well this way is really easy and very efficient the only thin you want is access to your friends computer and at least 45 seconds.
The following are the steps to do it:
Step 1: Open the firefox.
Step 2: Go to Tools -> Options -> Privacy -> Passwords
Step 3: There you will find the Show Password button , Just click on it.
Step 4: Now you can see the Password along with Websites. Note them down ;)
Step 1: Open Chrome
Step 2: Goto settings -> Options
Step 3: Goto Personal stuff -> Show saved passwords
Impress you friend.
WARNING: You can be punched on nose if you do something stupid with his/her accounts.