How to -create- performance issues? - oracle I want to dedicate some time to learn more about performance and tuning issues.
I assign for that a clean DB. I want to know how can I load into it some data and performance-problem queries/DML/DDL?
Do you know some scripts that can cause/generate that (purposely or not)?

The idea is to learn the basic(and maybe more) of em/awr/addm etc - tuning and performance wise. I dont really know what specific to ask, but I'm guessing index problems, selects issues, wrong way to access the data, etc..

Books are great but I have the knowledge I need some actual work on that. 

Maybe its not a Q&amp;A at all, but for me any answer (as long as it is an answer to my question) will do.

EDIT
I dont want just a server load script - because thats has no point, plus thats not what I want.
This is a pretty broad topic that would largely depend on your specific needs.  

Here is a link to a fairly recent article about load testing tools.   It provides pros and cons of several different options:

http://www.pythian.com/blog/oracle-database-load-testing-tools-overview/

Personally, I like the Silly Little Oracle Benchmark (SLOB).  http://kevinclosson.wordpress.com/2013/05/02/slob-2-a-significant-update-links-are-here/