One at a time.

Going slow and steady for your first time is doctor recommended, after all. You learned that in health class. Even better to start with someone undoubtedly as inexperienced as you. "Haaa.... As much as I'd love to take you on both at the same time, I'm pretty new to the whole sex thing." You once again lock eyes with the goblin still positioned in your lap. "Would you like to take the first step, Goldo?" Hearing this springs not only a stuttered response, but also the sputtered release of a few drops of pre-cum from his respectable member, even by human standards. Feeling this against your own rapidly thickening manhood leaves the question all but answered, only further answered by the response of several failed sentences only concluding with a faltering "Yes".

Aided by his verbal answer, you verbalize to the shorter one your intentions. "I'll get to you soon, Golbin, don't think I could handle a stud like you on my first try after all." Half of this is ego stroking to calm the little guy down enough to wait his turn, and the other half is the truthful observation of the disparity in the cock sizes between the two goblins.

"Heh, human smart. Goldo dick is nothing compared to mine. Two whole inches longer!" he says, holding up two of his fingers in utter confidence that this will impress you. He not wrong either. What your feeling up right now is a solid seven inch dick, impressive even for a human, to think that something so short could be hauling a cock that large is a wonder of biology to say the least. An even bigger surprise being when Goldo speaks up for himself, asserting that "Golbin may be longer, but Goldo is thicker!" in an attempt to save face in front of their new human friend.