title: regular expression - to find first value not matching a constant string in comma-separated list
body: <p>Title says it all. I am trying to build a regular expression but failing miserably. The task is to return the first string in a comma-separated list that is NOT matching a 'forbidden' constant string. The 'forbidden' string can occur anywhere in the list and (in theory) could occur multiple times in the list.</p>
  
  <p>For example (When the 'forbidden' string = "TBD"):</p>
  
  <pre><code>"TBD,Smith" --&gt; need to return Smith
  "TBD,TBD,TBD,Jones,Edwards" --&gt; need to return Jones
  "ABC,TBD,Smith" --&gt; need to return ABC
  "TBD,DEF-9gh,GHI,JKLMNOpqrst,Any old string" --&gt; need to return DEF-9gh
  </code></pre>
  
  <p>Any regex ninjas out there who know how to do this?</p>