ethernet cable extenders safe to use?

[captain420 3,019]

I currently have a 25foot ethernet cable in my room, but for my new setup it will need to be longer. Instead of purchasing a new cable, can I use a coupler or extension and just plug in another ethernet cable to the coupler to extend the length? I need about another 5-10 feet only. Or would this degrade my network performance?

[DaveCT2003 1,768]

Should be just fine.  I would get a quality one though.