I'm surprised you didn't use the "two hounds" definition from . I am not a legal expert, nor do I purport to give legal advice. Our rules are written the way they are written to maintain some semblance of order and to cover the EnviroLink Network's legal rear if there are problems.
When I use the word "couple" in the rules, it is the common reference for two things (in this case, sentences). As jhawk attempts to cheekily point out, there is no exact standard for how long the sentences should be, unless I gave you the number of characters (including spaces) that you are allowed to use. Due to the potential length of sentences, I could easily imagine a copyright challenge on two fully copied sentences, if you had two really, really long ones. So, the "first couple of sentences" (but definitely no more than two) will have to be your guide.
Rather than waste everyone's time defining every last thing, we'll let everyone use their
judgement and restrain their postings to a length that seems right, such as "a couple of sentences."
Thank you for the mind-numbing excursion into semantic variability.
-josh