Recording on cassette tapes

To be able to record an already recorded cassette tape you have to cover the small squared holes that you can see in the picture above. To cover them you can use for example duct tape

(which is, by the way, one of the world's greatest things :D)

So when you've put the tape on the tape (ehehee) it's (hopefully) ready to be re-recorded!

This is sick! I didn't knew this before my friend explained it to me a couple of weeks ago!

Good luck!