Twin's Surprise, Part 2

Twin's Surprise, Part 2 by cactusman

But the urge to cum is getting to be overwhelming. You beg her:

"Please... please, you'd better... you'd better let me stop! I can't take it!"

"Oh, already?"

"Yes," you say breathing hard. "It will make me ache more," you hesitate, "if you make me stroke it very slowly..."

"Why?"

"I don't know," you explain, "it just works that way..."