How to do this?

1) Copy-paste the URL from Google Map in this tool.

2) Copy-paste the script generated back into your post. That's it!

Below is the script that was generated for the map above:

<div><div style="left: 0px; width: 100%; height: 0px; position: relative; padding-bottom: 75.0019%;"><iframe src="//cdn.iframe.ly/htyLC3" frameborder="0" allowfullscreen="true" webkitallowfullscreen="true" mozallowfullscreen="true" style="top: 0px; left: 0px; width: 100%; height: 100%; position: absolute;"></iframe></div></div>

Cheers!