This picture is from last year, but please don't let that detract from its sublime dorkiness.
My only regret is that we'll never know how it ended. Did Federer switch to the dap just as Sampras opened his palm, thus starting an embarrassing ballet of mixed-up hand celebrations? Did one of the tennis greats sense the impending awkwardness and contort his hand in time? Or was the unorthodox fist-in-hand used and then unconvincingly passed off as the intended outcome?