There are various ways to call attention to yourself in a bathroom, and if you're cruising for some anonymous ass, writing on the wall is one way to do it. That's what Jack was doing when James walked in. Immediately, James knew that all he had to do was stick his fat cock through the gloryhole, and Jack would take it in his mouth.
The total strangers take turns sucking each other, getting those dicks as deep into their mouths as they can. James, feeling like he needs that cock somewhere else, presses his ass against the gloryhole, and begs for Jack's dick. Jack, also hungry for the man on the other side of the wall, slips his huge rod through the gloryhole, and into James' willing ass. Going slowly at first, they quickly pick up the pace...
While the gloryhole has plenty of advantages, Jack and James decide it's time to meet in the middle stall. While they continue to have fun, a third person, Rick, walks into the stall next to them. He's quickly invited by Jack to suck and, eventually, fuck James through the hole. Rick has his way with James, slams his dick nice and hard into him, and eventually cums in his ass.
Never having seen Jack's face, Rick takes off without even pulling up his pants. This leaves Jack and James with some privacy to finish each other off. Jack buries his cock nice and hard in James again, and comes all over his tight man hole. Wanting to get a nice taste of everything, James takes Jack in his mouth again, while he strokes himself to climax.