"You forgot, Loki, I'm not an Avenger," he then said, not really sure whether or not to take offense to being compared to Captain America.
Now here came the mental gymnastics - the way Loki let his expression slip when looking at the cards? Obvious a ploy, because Stephen knew Loki was a much better bluffer than that. Did he actually have a good hand, but was pretending it was bad? Then again, Loki would know that Stephen was watching, and could actually have a lousy hand and was trying to fake him out that by using reverse psychology.
What Stephen did know was his own cards were lousy. If only he could keep the hand he had from before. What was Loki doing, leaning forward? Ignore him, back to the game. If Loki wanted to bluff, he was going to get one in return.
Smiling ever so slightly, he leaned back and said, "Let's make this a little more interesting, shall we? Since you cheated, let's raise the stakes. In addition to the favor..." his smile widened a little more, but purposely hid it for Loki's sake "... If you win, you get the Scepter that I won from you in our 1950's tennis match." A status symbol for superiority that Stephen had hanging on his bedroom wall to this ever day. "And if I win, I get that slot machine you're always talking about." This time, Stephen smiled so wide his teeth showed. "What say you?"