He's not massaging his ass! He's using it as a pillow and that
is something I've done with platonic friends. No one would speculate there's something sexual going on in that scenario... if anything you're setting yourself up to be farted on by your buddy.
That clip was good for something though: Reminding me of Tully cracking it at Drew for not telling her about Tim's fake birthday. Because heaven forbid Drew keeps a joke secret for his friend. I honestly don't understand why you adore her so much when even some of her real-life friends are bailing on her. I guess that's what keeps the forum interesting though!