Has no desire to put his buddies cock in his mouth, but a bet is a bet. 

He figures he can just get this over with and forget about it. He does not yet understand that once you slurp on a dudes dick and swallow a his load, things can never go back to the way they were.  The balance of power has shifted.  He is no longer what he was, now he is a cocksucker. Every time his “friend” looks at him, he will remember the sight of his big cock aggressively pounding into his face. He will remember the feeling of superiority and domination of forcing his “buddy” to be his bitch. His “friend” will know that any time he needs to bust a nut, that mouth-cunt will be available.  After all, once it is used as a cum dump, that is what it will always be.