How to convert codebase to a hard-to-rip version?

How to convert codebase to a hard-to-rip version?

References

Reference NO 1

http://stackoverflow.com/questions/6388649/best-ways-to-become-familiar-with-a-perl-codebase

Reference NO 2

http://stackoverflow.com/questions/387815/how-do-you-familiarize-with-a-codebase-that-has-no-documentation

Reference NO 3

http://www.joelonsoftware.com/articles/fog0000000069.html

Reference NO 4

http://programmers.stackexchange.com/questions/155488/ive-inherited-200k-lines-of-spaghetti-code-what-now

Reference NO 5

http://joblivious.wordpress.com/2009/02/13/the-obsessive-programmers-guide-to-surviving-a-real-job/

Reference NO 6

http://codebase64.org/doku.php?id=base:demo_coding_introduction

Reference NO 7

http://developers.slashdot.org/story/13/06/20/1548228/are-you-sure-this-is-the-source-code

Reference NO 8

http://umbraco.com/follow-us/blog-archive/2012/6/13/v5-rip.aspx