This was posted to AO3, but I'm finally getting around to posting it here, too. Hope you enjoy!
They were sitting in the cafe around the corner from the tower the first time it happened. Tony was drinking coffee, black, with a shot of espresso, while Loki was continuing his experimentation with Starbuck's drinks. Today's choice had come piled high with whipped cream, cinnamon, sprinkles, and loving disdain from Tony.
They'd taken a seat in the corner by a window. Neither questioned where they sat. Tony knew Loki liked to see as much of the room, and those in it, as possible. Tony just wanted to see Loki and let the caffeine and sun wake him up.
Facing the windows, Tony also had a pretty good view of the street and cars passing by.
Which is why he interrupted Loki mid-word to punch his arm and exclaim, "Red one!"
Loki's eyes widened with confusion and annoyance as Tony leaned back smugly in his seat. "Stark," Loki said threateningly, "would you like to explain what just happened?"
Tony released the laugh he'd been struggling to contain. "It's slug bug!"
"Care to run that one by me again?"
"Slug bug," Tony repeated. "When you see a VW Bug, you call out the color and punch everyone in the immediate vicinity."
"And why do you do this?" Part of Loki's meaning was clearly him being his same pointed self, but Tony knew him well enough to hear genuine curiosity beneath that.
He considered for a moment. "No one really knows why people do it," he finally admitted.
"And the first to identity the vehicle wins?"
He let out a short laugh. "No one really wins slug bug. Mostly, it just gives people excuses to punch their boyfriends."
And that was how Loki got turned onto slug bug and Tony soon came to regret introducing him to it because the guy took things WAY too seriously. Everywhere they went, Loki would call out colors and punch Tony.
Tony claimed that Loki had the unfair advantage of inhuman sight.
Loki replied that it was Tony's fault for taking him places he knew the cars could appear.
And Tony was starting to suspect that Loki was using his trickster magic to manifest the things, because there was no way that many of those stupid little cars would appear EVERY TIME THEY WENT OUTSIDE.
But of course, he couldn't prove it. He suspected he'd have to distract Loki from playing slug bug.
And he didn't mean making out with him, because he'd tried that and Loki had punched him in the arm and said, "Blue one!" without even breaking the kiss, damn him.
No, he had to get serious about this, find something else to occupy the trickster's time.
Which is how he found himself back at the same table at the same Starbuck's, smirking across the table at Loki as he slowly said, "I just lost the game."