Disclaimer
"pink slip" or work separation notice - optional in most states - not required in Texas
most states do not require an employer to give an explanation of the reason or reasons for discharge, and an employee is not required to give an explanation for a resignation - if given, make the explanation brief and to the point - the "pink slip is not the time to make an example of someone or to "rub it in" - in general, the shorter, the better.
some states require formal notice of termination, and a few states even require the employer to give the employee the specific reasons for discharge - as noted above, an employer should write down only the bare minimum needed.
above all, avoid inflammatory language or anything you cannot document - certain terms sound inherently defamatory, such as "thief", "stealing", or "drug abuse" - use non-inflammatory descriptive terms that can be documented, such as "failure to properly account for items entrusted to his care", or "violated drug-free workplace policy by testing positive for [whatever]"
the same goes for any oral explanations of the reasons for discharge - remember, an employee may be tape-recording the conversation - it is usually best to let one specific person in the organization carry out all terminations in order to minimize the risk that individual hard feelings might inadvertently result in statements that end up sounding defamatory in court.
supply a space for the employee's statement - an employee will often give an honest statement that can help the employer defend against an employment claim in the future