...ering cross between a whimper and a moan.
"Uhh!" he exclaimed, "I-it's so…warm, a-and tight! Oh, Ferb!" He panted heavily. Ferb lay there, adjusting, a sweat on his brow forming from his brother's hot words. He constricted and expanded alternately around Phineas, the expression on his face slowly losing all traces of pain.
When he felt loose enough, the hand he had around himself increased its pace, and he began to rock himself so that he slid up and down slightly on the table, creating friction.
Phineas' eyes became wide again as a trembling 'Ahh!' escaped him. On instinct he began to move with Ferb, hunching and moaning more as the friction increased to the point where he was starting to actually slide in and out of Ferb.
As Ferb became accustomed to the motion, the sliding became easier and more fluid. Phineas' thrusts became harder, and the pleasure for both of them mounted intensely. Ferb melted, no longer needing to rock himself to guide Phineas. He lay back, eyes closed, taking each thrust and letting the pleasure waves roll over him in droves as he stroked himself.
This went on for a while; Phineas thrusting inward, ever-enflamed by his brother's quiet gasps, the usual stoic face screwed up ever-so-slightly in ecstasy.
Eventually, however, it seemed that Ferb decided that it ...