I came across this while one person is asking another about playing video games. I can't figure out the くない (くんない) as a て-form verb ending.

You may see it as a spoken form of くれない, which is the negative form of くれる (i.e., くれる + ない = くれない). It's more informal and slightly slangy.

This shortening of a -ru + n sound to -nn is common. You see こっちくんな (こっち来るな), or どうすんの？ (どうするの？) for instance. Just this morning a man saw me eating a nattomaki and asked 納豆くえんのか？ (納豆食えるのか?)

Thanks for the help. I was wondering if it was a contraction or slang since I couldn't find anything in my references.