His last birthday had been kind of crap. Losing Bobby and coming out to Dean about his blood addiction had not been Sam's idea of a good time. Even if some people think Sam Winchester has no idea what a good time is, he is pretty damn confident that it isn't that. But in a way it had kind of been par for the course. Bad things happen to Winchesters. Bad things follow them. When it's not demons or angels or worse, it's their own bad decisions coming back to haunt them.
Which is why Sam's approaching this birthday with a tentative, cautious attitude. In some ways, it seems like nothing worse could possibly happen. Angua's gone. Castiel, Pam, Bobby, Dad, Ellen, Sharon. There has to be a limit on losing people and surely they've hit it, for the time being. Weird, dangerous shit happens to them all the time, but losing people hurts the worst. Sam doesn't expect to be able to hold onto the people he cares about on the island forever, but he hopes they can at least long enough for Dean to heal. Days keep going by without anyone they're close to disappearing and, selfishly, that's okay by Sam.
He's not enthusiastic enough to try for a party, which he hates anyway. No one pushes for one and that's fine by Sam. But it's a nice enough day, no trouble directly in sight, that Sam's willing to take a risk and enjoy something he hasn't really allowed himself in a year and a half on the island.
The art of bodysurfing is completely lost on Sam. He feels the pull of the wave as it crests but can't find the right pocket, the right speed and position. He never finds it, but for the most part he drifts over the top of the wave and finds the next or it crashes down around him and for two seconds it almost feels like he's riding the wave. He's not, just propelled along by the force, but it's enough fun that he does it again and again.
Until, that is, the inevitable happens. The wave crashes down on top of Sam, not around him, and he doesn't know which way is up anymore. He dings his funny bone on hard-packed sand and burns his knee, but he comes out of it in the end. Choking on salt water and feeling rung out, but alive. Somehow he got from deep water to knee-depth in the course of the wipeout, so there's no reason for him not to take a break on the shore and catch his breath.
He's still coughing as he moves to grab a seat on his towel, but there's the slightest smile on his face, too.
[Better than average time to meet him, actually. ST/LT welcome. Of note is his
tattoo and.. standard Sasquatch-like stature. Your pup probably won't know it's his birthday unless s/he is a close family friend.]