Joe Buck and the Internet think he said, "This is my guy!" But how sure are we? Alternate possibilities:
"This is my night!"
"This is mud cake!"
"This is my cake!"
"This is my mud cake tonight!"
Huh, turns out that I'm terrible at this. Makes you appreciate the people at Bad Lip Reading even more. He probably really said, "This is my guy." But if you have amusing alternate suggestions, have at it. He was about one syllable away from doing a Carl impersonation: